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Echolocation in humans
- Thread starterwet
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
It can take a long time to get an up-to-date response or contact with relevant users.
BPS Research Digest: The neuroscience of batman, or how the human brain performs echolocation
Over the last few years it’s become apparent that humans, like bats, can make effective use of echolocation by emitting click sounds with the tongue and listening for the echoes that result. Now a team led by Lore Thaler at the University of Western Ontario has conducted the first ever investigation into the neural correlates of this skill.
Among several remarkable new insights generated by the research, the most important is that EB and LB exhibited increased activity in their visual cortices, but not their auditory cortices, when they listened to clicks and echo recordings taken outside, compared with when they listened to the exact same recordings with the subtle echoes omitted. No such differential activity was detected among two age-matched, male sighted controls.
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They can see the echoes, but not hear them. Like dolphins, bats, aye-ayes, cave swifts I guess.
Over the last few years it’s become apparent that humans, like bats, can make effective use of echolocation by emitting click sounds with the tongue and listening for the echoes that result. Now a team led by Lore Thaler at the University of Western Ontario has conducted the first ever investigation into the neural correlates of this skill.
Among several remarkable new insights generated by the research, the most important is that EB and LB exhibited increased activity in their visual cortices, but not their auditory cortices, when they listened to clicks and echo recordings taken outside, compared with when they listened to the exact same recordings with the subtle echoes omitted. No such differential activity was detected among two age-matched, male sighted controls.
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They can see the echoes, but not hear them. Like dolphins, bats, aye-ayes, cave swifts I guess.
Photoacoustic imaging beyond our wildest dreams
Photoacoustic imaging represents a sort of "best of both" approach to (xray/ultrasonic/cat type) imaging. The basic process is that a relatively powerful pulse of light is sent into some part of the body. Wherever it is absorbed—it generates heat, as its target expands and generates a small acoustic pressure wave. By picking up these sound waves with microphones, an image of the absorbing structures can be built up.
In the original photoacoustic imaging technique, the image resolution was about the same as that of ultrasound. So you could use it for whole organ imaging and detect things like tumors, provided they were already a few millimeters large and had started developing their own blood supply—blood is generally where the light is absorbed, so what you actually get is a picture of the blood supply.
So, instead of flooding the tissue with light and getting image resolution on the order of the acoustic wavelength, you can focus the light and use the photoacoustic signal as a contrast mechanism for distinguishing absorption at the scale of the wavelength of light.
This has allowed Wang's team to go much further, imaging with a resolution that is capable of detecting capillaries—so basically they have cellular resolution. Because they are detecting absorption, they can distinguish between oxygenated and deoxygenated blood, which is nice.
But where they really hit the jackpot is detecting the oxygen saturation of the blood. This is a really important measure, as it seems that changes to oxygen saturation in the microcirculation can be predictive of a patient going into shock
see photo at link
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can dolphins see this too? Perhaps only at the skin surface?
Photoacoustic imaging represents a sort of "best of both" approach to (xray/ultrasonic/cat type) imaging. The basic process is that a relatively powerful pulse of light is sent into some part of the body. Wherever it is absorbed—it generates heat, as its target expands and generates a small acoustic pressure wave. By picking up these sound waves with microphones, an image of the absorbing structures can be built up.
In the original photoacoustic imaging technique, the image resolution was about the same as that of ultrasound. So you could use it for whole organ imaging and detect things like tumors, provided they were already a few millimeters large and had started developing their own blood supply—blood is generally where the light is absorbed, so what you actually get is a picture of the blood supply.
So, instead of flooding the tissue with light and getting image resolution on the order of the acoustic wavelength, you can focus the light and use the photoacoustic signal as a contrast mechanism for distinguishing absorption at the scale of the wavelength of light.
This has allowed Wang's team to go much further, imaging with a resolution that is capable of detecting capillaries—so basically they have cellular resolution. Because they are detecting absorption, they can distinguish between oxygenated and deoxygenated blood, which is nice.
But where they really hit the jackpot is detecting the oxygen saturation of the blood. This is a really important measure, as it seems that changes to oxygen saturation in the microcirculation can be predictive of a patient going into shock
see photo at link
-
can dolphins see this too? Perhaps only at the skin surface?
irrelevant tidbit: rainforest plant employs echolocation to draw bats
BBC Nature - Plant evolved a bat beckoning beacon
Might there be a parallel in water for dolphins?
Large clamshells probably echo sonar, but dolphins don't eat hardshell clams. (Some eat molluscs which contain small internal vestigial shells, like squid, which would be detectable by sonar)
BBC Nature - Plant evolved a bat beckoning beacon
Might there be a parallel in water for dolphins?
Large clamshells probably echo sonar, but dolphins don't eat hardshell clams. (Some eat molluscs which contain small internal vestigial shells, like squid, which would be detectable by sonar)
Last edited:
Parallel: bats echolocate, vampire bats use trigeminal nerve to detect infrared light (heat radiation) of blood flow in victims, while pit vipers (eg. rattlesnakes) use their pit organs (smell related) to detect infrared radiation in prey.
ARC theory states that ancestral coastal human diving foragers employed a generalized form of echolocation (as opposed to super-tuned pelagic dolphin/flying bat style of echolocation) and also employed the trigeminal nerve in light detection for respirational function during cyclical foraging dive sequences.
-
Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats
EO Gracheva ... D Julius 2011
Nature 476:88*91 doi 10.1038/nature10245
Desmodus rotundus are obligate blood feeders that have evolved specialized
systems to suit their sanguinary lifestyle.
Chief among such adaptations is the ability to detect infra-red radiation
as a means of locating hotspots on warm-blooded prey.
Among vertebrates, only vampire bats, boas, pythons & pit vipers are
capable of detecting IR radiation.
In each case, IR signals are detected by trigeminal nerve fibres that
innervate specialized pit organs on the animal's face.
Thus, vampire bats & snakes have taken thermo-sensation to the extreme by
developing specialized systems for detecting IR radiation.
As such, these creatures provide a window into the molecular & genetic
mechanisms underlying evolutionary tuning of thermo-receptors in a
species-specific or cell-type-specific manner.
Previously, we have shown that snakes co-opt a non-heat-sensitive channel,
vertebrate TRPA1 (transient receptor potential cation channel A1), to
produce an IR detector.
Here we show that vampire bats tune a channel that is already
heat-sensitive, TRPV1, by lowering its thermal activation threshold to c
30°C.
This is achieved through alternative splicing of TRPV1 transcripts to
produce a channel with a truncated carboxy-terminal cytoplasmic domain.
These splicing events occur exclusively in trigeminal ganglia, not in
dorsal root ganglia, thereby maintaining a role for TRPV1 as a detector of
noxious heat in somatic afferents.
This reflects a unique organization of the bat Trpv1 gene that we show to
be characteristic of Laurasiatheria mammals (cows, dogs & moles),
supporting a close phylogenetic relationship with bats.
These findings reveal a novel molecular mechanism for physiological tuning
of thermo-sensory nerve fibres.
______
How Vampire Bats Find Veins
Heat-sensing protein channels allow to find the best place to sink their
teeth into the prey
Jessica P Johnson 4.8.11
Researchers have discovered an IR-sensing protein channel that allows
vampire bats to identify the hottest part of the animal ‹ veins close to
the skin's surface that carry 38°C blood, and presumably the best spot for
feeding.
The channel is a variant of TRPV1, a heat-sensing protein channel,
triggered by high Tps that could potentially cause injury, distinct from
the heat sensor used by snakes ‹ the only other non-insect animals that
are known to detect heat by sensing IR radiation.
Bill Schutt (Long Island Univ., not involved in the research): "Infrared
[detection] allows these guys, in pitch black, to hunt down warm-blooded
prey." The researchers identified a modification in a common heat-sensing
protein channel that lowered its Tp threshold, so that it is more attuned
to an animal's body heat.
The common vampire bat was appropriately named after the myth of Dracula ‹
it feeds at night and lives solely on a diet of blood, every day or 2
consuming up to half its weight in the vital substance from large mammals,
esp.sleeping livestock.
The bats first use echo-location to detect their prey, but once they are
within 20 cm of their target, they use IR sensors in specialized pits
around their noses to zero in on the best place to feed.
In a previous study, physiologist David Julius (Univ.California SF) &
colleagues found that IR detection by snakes ‹ which, like bats, use
nerves located in facial pits to detect their prey ‹ is mediated by a
cell-surface protein channel called transient receptor potential cation
channel A1 (TRPA1).
The channel is actually insensitive to heat in most organisms, but had
evolved the capability in snakes, leading the group to suspect that a
similar
transformation may have given vampire bats their ability to sense IR.
To see if this was the case, Julius cs compared gene expression in vampire
bats' heat-sensing nerves (trigeminal ganglia) with expression in a nerve
cluster near the spine (dorsal root ganglia DRG).
They also compared these expression patterns to those of the ganglia in 4
bat spp that do not have IR sensory abilities.
To their surprise, they did not observe any differences in transcription
of the TRPA1-coding gene, nor of any other genes.
Instead, they discovered that the protein TRPV1 ‹ a heat-sensing protein
channel normally triggered by Tps >43°C ‹ existed in 2 different isoforms
‹ a c 850-AA version & one 62 AAs shorter.
The short form, which resulted from alternative splicing of the
transcribed mRNA, made up 1/2 of the TRPV1 found in the trigeminal ganglia
of vampire bats - it comprised only a small % of the TRPV1 in the DRG.
It was similarly low in both types of nerve clusters in the other bat spp,
so the short form may play a role in IR detection.
The researchers expressed 1 of the 2 TRPV1 isoforms in human kidney cells
& in frog oocytes grown in vitro, and measured their Tp sensitivity using
Ca imaging & electro-physiological assays resp.
As expected, cells producing the long isoform were activated at 40°C.
Cells producing the short isoform were activated at just 30°C ‹ a drop
that allows the protein to respond to the warmth of the vampire bats' prey.
Brock Fenton (biol.Univ.W-Ontario, Nature N&V paper): "This is a big jump
in understanding how these animals locate their prey."
While the longer isoform maintains its normal function of detecting
potentially harmful high Tps, the shorter isoform in the trigeminal nerves
of the common vampire bat allows the animals to detect lower Tps, such as
the body heat of their mammalian prey.
Schutt (2008 "Dark Banquet: Blood and the Curious Lives of Blood-Feeding
Creatures"): "Basically, evolution tweaked a system in vampires bats that
was
already being used to sense Tps," turning it into a useful hunting tool.
This is in contrast to the pit viper, whose IR-sensing ability evolved
from a different type of channel, not involved in heat detection, but in
the detection of noxious smells, added Fenton: the different evolutionary
strategies employed by these 2 lineages "is an example of how plastic our
sensory systems can be."
ARC theory states that ancestral coastal human diving foragers employed a generalized form of echolocation (as opposed to super-tuned pelagic dolphin/flying bat style of echolocation) and also employed the trigeminal nerve in light detection for respirational function during cyclical foraging dive sequences.
-
Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats
EO Gracheva ... D Julius 2011
Nature 476:88*91 doi 10.1038/nature10245
Desmodus rotundus are obligate blood feeders that have evolved specialized
systems to suit their sanguinary lifestyle.
Chief among such adaptations is the ability to detect infra-red radiation
as a means of locating hotspots on warm-blooded prey.
Among vertebrates, only vampire bats, boas, pythons & pit vipers are
capable of detecting IR radiation.
In each case, IR signals are detected by trigeminal nerve fibres that
innervate specialized pit organs on the animal's face.
Thus, vampire bats & snakes have taken thermo-sensation to the extreme by
developing specialized systems for detecting IR radiation.
As such, these creatures provide a window into the molecular & genetic
mechanisms underlying evolutionary tuning of thermo-receptors in a
species-specific or cell-type-specific manner.
Previously, we have shown that snakes co-opt a non-heat-sensitive channel,
vertebrate TRPA1 (transient receptor potential cation channel A1), to
produce an IR detector.
Here we show that vampire bats tune a channel that is already
heat-sensitive, TRPV1, by lowering its thermal activation threshold to c
30°C.
This is achieved through alternative splicing of TRPV1 transcripts to
produce a channel with a truncated carboxy-terminal cytoplasmic domain.
These splicing events occur exclusively in trigeminal ganglia, not in
dorsal root ganglia, thereby maintaining a role for TRPV1 as a detector of
noxious heat in somatic afferents.
This reflects a unique organization of the bat Trpv1 gene that we show to
be characteristic of Laurasiatheria mammals (cows, dogs & moles),
supporting a close phylogenetic relationship with bats.
These findings reveal a novel molecular mechanism for physiological tuning
of thermo-sensory nerve fibres.
______
How Vampire Bats Find Veins
Heat-sensing protein channels allow to find the best place to sink their
teeth into the prey
Jessica P Johnson 4.8.11
Researchers have discovered an IR-sensing protein channel that allows
vampire bats to identify the hottest part of the animal ‹ veins close to
the skin's surface that carry 38°C blood, and presumably the best spot for
feeding.
The channel is a variant of TRPV1, a heat-sensing protein channel,
triggered by high Tps that could potentially cause injury, distinct from
the heat sensor used by snakes ‹ the only other non-insect animals that
are known to detect heat by sensing IR radiation.
Bill Schutt (Long Island Univ., not involved in the research): "Infrared
[detection] allows these guys, in pitch black, to hunt down warm-blooded
prey." The researchers identified a modification in a common heat-sensing
protein channel that lowered its Tp threshold, so that it is more attuned
to an animal's body heat.
The common vampire bat was appropriately named after the myth of Dracula ‹
it feeds at night and lives solely on a diet of blood, every day or 2
consuming up to half its weight in the vital substance from large mammals,
esp.sleeping livestock.
The bats first use echo-location to detect their prey, but once they are
within 20 cm of their target, they use IR sensors in specialized pits
around their noses to zero in on the best place to feed.
In a previous study, physiologist David Julius (Univ.California SF) &
colleagues found that IR detection by snakes ‹ which, like bats, use
nerves located in facial pits to detect their prey ‹ is mediated by a
cell-surface protein channel called transient receptor potential cation
channel A1 (TRPA1).
The channel is actually insensitive to heat in most organisms, but had
evolved the capability in snakes, leading the group to suspect that a
similar
transformation may have given vampire bats their ability to sense IR.
To see if this was the case, Julius cs compared gene expression in vampire
bats' heat-sensing nerves (trigeminal ganglia) with expression in a nerve
cluster near the spine (dorsal root ganglia DRG).
They also compared these expression patterns to those of the ganglia in 4
bat spp that do not have IR sensory abilities.
To their surprise, they did not observe any differences in transcription
of the TRPA1-coding gene, nor of any other genes.
Instead, they discovered that the protein TRPV1 ‹ a heat-sensing protein
channel normally triggered by Tps >43°C ‹ existed in 2 different isoforms
‹ a c 850-AA version & one 62 AAs shorter.
The short form, which resulted from alternative splicing of the
transcribed mRNA, made up 1/2 of the TRPV1 found in the trigeminal ganglia
of vampire bats - it comprised only a small % of the TRPV1 in the DRG.
It was similarly low in both types of nerve clusters in the other bat spp,
so the short form may play a role in IR detection.
The researchers expressed 1 of the 2 TRPV1 isoforms in human kidney cells
& in frog oocytes grown in vitro, and measured their Tp sensitivity using
Ca imaging & electro-physiological assays resp.
As expected, cells producing the long isoform were activated at 40°C.
Cells producing the short isoform were activated at just 30°C ‹ a drop
that allows the protein to respond to the warmth of the vampire bats' prey.
Brock Fenton (biol.Univ.W-Ontario, Nature N&V paper): "This is a big jump
in understanding how these animals locate their prey."
While the longer isoform maintains its normal function of detecting
potentially harmful high Tps, the shorter isoform in the trigeminal nerves
of the common vampire bat allows the animals to detect lower Tps, such as
the body heat of their mammalian prey.
Schutt (2008 "Dark Banquet: Blood and the Curious Lives of Blood-Feeding
Creatures"): "Basically, evolution tweaked a system in vampires bats that
was
already being used to sense Tps," turning it into a useful hunting tool.
This is in contrast to the pit viper, whose IR-sensing ability evolved
from a different type of channel, not involved in heat detection, but in
the detection of noxious smells, added Fenton: the different evolutionary
strategies employed by these 2 lineages "is an example of how plastic our
sensory systems can be."
Last edited:
Elephant fish has big cerebellum (like humans) and high intelligence, uses electric field to locate invertebrate prey. Has odd ears.
[ame="http://en.wikipedia.org/wiki/Mormyridae"]Mormyridae - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:Gnathonemuspetersii.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Gnathonemuspetersii.jpg/250px-Gnathonemuspetersii.jpg"@@AMEPARAM@@commons/thumb/4/45/Gnathonemuspetersii.jpg/250px-Gnathonemuspetersii.jpg[/ame]
unexpected similarities in 'snorkeled' fish & humans
[ame="http://en.wikipedia.org/wiki/Mormyridae"]Mormyridae - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:Gnathonemuspetersii.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Gnathonemuspetersii.jpg/250px-Gnathonemuspetersii.jpg"@@AMEPARAM@@commons/thumb/4/45/Gnathonemuspetersii.jpg/250px-Gnathonemuspetersii.jpg[/ame]
unexpected similarities in 'snorkeled' fish & humans
Dolphins 'Talk' Like Humans, New Study Suggests | Bottlenose Dolphins & Dolphin Communication | Dolphin Whistles & Human Sounds | LiveScience
New research suggests the whistles of bottlenose dolphins aren't whistles
at all.
Dolphins "talk" to each other, using the same process to make their
high-pitched sounds as humans, according to a new analysis of results from
a 1970s experiment.
The findings mean dolphins don't actually whistle as has been long
thought, but instead rely on vibrations of tissues in their nasal cavities
that are analogous to our vocal cords.
Scientists are only now figuring this out, "because it certainly sounds
like a whistle," said study researcher Peter Madsen (Biology Letters, Inst
Biosci Aarhus Univ), adding that the term was coined in a paper published
in 1949 in the journal Science. "And it has stuck since."
The finding clears up a question that has long puzzled scientists:
How can dolphins make their signature identifying whistles at the water's
surface and during deep dives where compression causes sound waves to
travel faster and would thus change the frequency of those calls.
Madsen cs analyzed recently digitized recordings of a 12-year-old male
Tursiops truncatus from 1977.
At the time, the researchers had the dolphin breathe a mixture of helium &
oxygen called heliox (used by humans, it makes one sound like Donald Duck).
The heliox was meant to mimic conditions during a deep dive since it
causes a shift up in frequency.
When breathing air or heliox, the male dolphin, however, continued to make
the same whistles, with the same frequency.
Rather than vocal cords, the dolphins likely use tissue vibrations in
their nasal cavities to produce their "whistles", which aren't true
whistles after all.
The researchers suggest structures in the nasal cavity, "phonic lips", are
responsible for the sound.
The dolphins aren't actually talking, though.
"It does not mean that they talk like humans, only that they communicate
with sound made in the same way.
Cetacean ancestors lived on land some 40 Ma and made sounds with vocal
folds in their larynx.
They lost that during the adaptations to a fully aquatic lifestyle, but
evolved sound production in the nose that functions like that of vocal
folds."
This vocal ability also likely gives dolphins a broader range of sounds.
"Because the frequency is changed by changing the airflow and the tension
of the connective tissue lips in the nose, the dolphin can change
frequency much faster than if it had to do it by changing air sac volumes.
That means that there is a much bigger potential for making a broader
range of sounds and hence increase information transfer."
-
Dolphins do have vocal chords (muscle tissue & associated tensional tissue), but they have been greatly modified from the typical mammal; elevated into the nasal region rather than in the throat (dolphins can't breathe through their mouths). Lions and chimps can vocalize both on inhale (false vocal chords) and exhale (normal vocal chords), humans mostly vocalize on exhale (normal vocal chords).
New research suggests the whistles of bottlenose dolphins aren't whistles
at all.
Dolphins "talk" to each other, using the same process to make their
high-pitched sounds as humans, according to a new analysis of results from
a 1970s experiment.
The findings mean dolphins don't actually whistle as has been long
thought, but instead rely on vibrations of tissues in their nasal cavities
that are analogous to our vocal cords.
Scientists are only now figuring this out, "because it certainly sounds
like a whistle," said study researcher Peter Madsen (Biology Letters, Inst
Biosci Aarhus Univ), adding that the term was coined in a paper published
in 1949 in the journal Science. "And it has stuck since."
The finding clears up a question that has long puzzled scientists:
How can dolphins make their signature identifying whistles at the water's
surface and during deep dives where compression causes sound waves to
travel faster and would thus change the frequency of those calls.
Madsen cs analyzed recently digitized recordings of a 12-year-old male
Tursiops truncatus from 1977.
At the time, the researchers had the dolphin breathe a mixture of helium &
oxygen called heliox (used by humans, it makes one sound like Donald Duck).
The heliox was meant to mimic conditions during a deep dive since it
causes a shift up in frequency.
When breathing air or heliox, the male dolphin, however, continued to make
the same whistles, with the same frequency.
Rather than vocal cords, the dolphins likely use tissue vibrations in
their nasal cavities to produce their "whistles", which aren't true
whistles after all.
The researchers suggest structures in the nasal cavity, "phonic lips", are
responsible for the sound.
The dolphins aren't actually talking, though.
"It does not mean that they talk like humans, only that they communicate
with sound made in the same way.
Cetacean ancestors lived on land some 40 Ma and made sounds with vocal
folds in their larynx.
They lost that during the adaptations to a fully aquatic lifestyle, but
evolved sound production in the nose that functions like that of vocal
folds."
This vocal ability also likely gives dolphins a broader range of sounds.
"Because the frequency is changed by changing the airflow and the tension
of the connective tissue lips in the nose, the dolphin can change
frequency much faster than if it had to do it by changing air sac volumes.
That means that there is a much bigger potential for making a broader
range of sounds and hence increase information transfer."
-
Dolphins do have vocal chords (muscle tissue & associated tensional tissue), but they have been greatly modified from the typical mammal; elevated into the nasal region rather than in the throat (dolphins can't breathe through their mouths). Lions and chimps can vocalize both on inhale (false vocal chords) and exhale (normal vocal chords), humans mostly vocalize on exhale (normal vocal chords).
Correction: dolphins have 2 sets of vocal chords, but use only one set while both whistling and clicking (buzzing a sonar beam).
Single source sound production and dynamic beam formation in echolocating harbour porpoises (Phocoena phocoena)
"All non-physeteroid toothed whales have two pairs of phonic lips allowing many of these species to produce both whistles and clicks at the same time. That has led to the hypothesis that toothed whales can increase the power outputs and bandwidths of clicks, and enable fast clicking and beam steering by acutely timed actuation of both phonic lip pairs simultaneously. Here we test that hypothesis by applying suction cup hydrophones on the sound-producing nasal complexes of three echolocating porpoises (Phocoena phocoena) with symmetrical pairs of phonic lips. Using time of arrival differences on three hydrophones, we show that all recorded clicks from these three porpoises are produced by the right pair of phonic lips with no evidence of simultaneous or independent actuation of the left pair.
response by aquatic amniotes blog:
The Aquatic Amniote
"But these researchers did something very clever – they attached suction-cupped microphones to both pairs of phonic lips of a porpoise to basically see whether both pairs were functioning to produce whistles. They weren’t, as one could glean from the title, and this has major implications for the functional role of the second pair of phonic lips, as well as questions about the evolutionary loss of them in sperm whales."
-
I'd think the second phonic lip pair was engaged in respiration control, while in physeteroids (sperm whales) this was controlled nasally.
-
Interesting to compare to ARC theory, 'dive song': one partner aerobic humming while backfloating and the other submerged apneic clicking at depth, for both communication and some sonar echolocation. Only the humming uses vocal chords, clicking uses tongue and lips.
Single source sound production and dynamic beam formation in echolocating harbour porpoises (Phocoena phocoena)
"All non-physeteroid toothed whales have two pairs of phonic lips allowing many of these species to produce both whistles and clicks at the same time. That has led to the hypothesis that toothed whales can increase the power outputs and bandwidths of clicks, and enable fast clicking and beam steering by acutely timed actuation of both phonic lip pairs simultaneously. Here we test that hypothesis by applying suction cup hydrophones on the sound-producing nasal complexes of three echolocating porpoises (Phocoena phocoena) with symmetrical pairs of phonic lips. Using time of arrival differences on three hydrophones, we show that all recorded clicks from these three porpoises are produced by the right pair of phonic lips with no evidence of simultaneous or independent actuation of the left pair.
response by aquatic amniotes blog:
The Aquatic Amniote
"But these researchers did something very clever – they attached suction-cupped microphones to both pairs of phonic lips of a porpoise to basically see whether both pairs were functioning to produce whistles. They weren’t, as one could glean from the title, and this has major implications for the functional role of the second pair of phonic lips, as well as questions about the evolutionary loss of them in sperm whales."
-
I'd think the second phonic lip pair was engaged in respiration control, while in physeteroids (sperm whales) this was controlled nasally.
-
Interesting to compare to ARC theory, 'dive song': one partner aerobic humming while backfloating and the other submerged apneic clicking at depth, for both communication and some sonar echolocation. Only the humming uses vocal chords, clicking uses tongue and lips.
While dolphins and sperm whales have highly developed echolocation, mysticetes (eg. blue & balleen whales) do not use echolocation, but do have good hearing. Interestingly, this study finds that archaic ancestors of all whales developed sensitivity to prey sounds, based on cranial asymmetry:
JM Fahlke, PD Gingerich, RC Welsh & AR Wood 2011 PNAS press
Cranial asymmetry in Eocene archaeocete whales and the evolution of
directional hearing in water
Eocene archaeocetes gave rise to all modern toothed & baleen whales (Odontoceti & Mysticeti) during or near the Eo-Oligocene transition.
1) Odontocetes (dolphins, Orca, one blowhole) have asymmetrical skulls, with asymmetry linked to
- high-frequency sound production &
- echo-location.
2) Mysticetes (balleen whales, 2 blowholes) are generally assumed to have symmetrical skulls, and lack
high-frequency hearing.
Here we show that protocetid & basilosaurid archaeocete ("ancestral whales") skulls are distinctly & directionally asymmetrical.
Archaeocete asymmetry involves curvature & axial torsion of the cranium, but no telescoping.
Cranial asymmetry evolved in Eocene archaeocetes as part of a complex of traits linked to directional hearing (pan-bone thinning of the lower jaws, mandibular fat pads, isolation of the ear region), probably enabling them to hear the higher sonic frequencies of sound-producing fish on which they preyed.
Ultra sonic echolocation evolved in Oligocene odontocetes, enabling them to find silent prey.
Asymmetry & much of the sonic-frequency range of directional hearing were lost in Oligocene mysticetes, during the shift to low-frequency hearing & bulk-straining predation (masses of krill & schools of small fish rather than fast large fish & squid).
-
Although aquatic-foraging human ancestors did not chase fish, they may have detected the position of sounds of prey, and coralled them in some way, using various methods (stone wall/cairn/weirs, fence-nets, driving them into small lagoons or mud banks as some dolphins do). Acoustic detection would supplement visual clues (sea bird flocks above schools).
JM Fahlke, PD Gingerich, RC Welsh & AR Wood 2011 PNAS press
Cranial asymmetry in Eocene archaeocete whales and the evolution of
directional hearing in water
Eocene archaeocetes gave rise to all modern toothed & baleen whales (Odontoceti & Mysticeti) during or near the Eo-Oligocene transition.
1) Odontocetes (dolphins, Orca, one blowhole) have asymmetrical skulls, with asymmetry linked to
- high-frequency sound production &
- echo-location.
2) Mysticetes (balleen whales, 2 blowholes) are generally assumed to have symmetrical skulls, and lack
high-frequency hearing.
Here we show that protocetid & basilosaurid archaeocete ("ancestral whales") skulls are distinctly & directionally asymmetrical.
Archaeocete asymmetry involves curvature & axial torsion of the cranium, but no telescoping.
Cranial asymmetry evolved in Eocene archaeocetes as part of a complex of traits linked to directional hearing (pan-bone thinning of the lower jaws, mandibular fat pads, isolation of the ear region), probably enabling them to hear the higher sonic frequencies of sound-producing fish on which they preyed.
Ultra sonic echolocation evolved in Oligocene odontocetes, enabling them to find silent prey.
Asymmetry & much of the sonic-frequency range of directional hearing were lost in Oligocene mysticetes, during the shift to low-frequency hearing & bulk-straining predation (masses of krill & schools of small fish rather than fast large fish & squid).
-
Although aquatic-foraging human ancestors did not chase fish, they may have detected the position of sounds of prey, and coralled them in some way, using various methods (stone wall/cairn/weirs, fence-nets, driving them into small lagoons or mud banks as some dolphins do). Acoustic detection would supplement visual clues (sea bird flocks above schools).
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OT but interesting: humans, but not apes
Hindawi Publishing Corporation
Mediators of Inflammation Article ID 321494 11pp
doi 10.1155/2010/321494
Review Article
Surface Lipids as Multifunctional Mediators of Skin Responses to
Environmental Stimuli
Chiara De Luca & Giuseppe Valacchi 2010
Philip W Wertz ed
open access
Skin surface lipid (SSL) film is a mixture of sebum & keratinocyte membrane
lipids, protecting skin from environment.
Its composition is unique for the high % of
- long-chain fatty acids (FAs) &
- the poly-terpenoid squalene (SQ), absent in other human tissues & in
non-human Primates sebum.
Here, the still incomplete body of information on SSL as mediators of
external chemical, physical & microbial signals & stressors is revised.
We focus on the central event of the continuous oxidative modification
induced by the metabolic activity of
- residential & pathological microbial flora,
- natural or iatrogenic UV irradiation,
- exposure to chemicals & cosmetics.
Once alpha-tocopherol & ubiquinol-10 anti-oxidant defences of SSL are
overcome, oxidation of SQ & cholesterol gives rise to reactive by-products
penetrating deeper into skin layers, to mediate local defensive
inflammatory, photo-protective, immune reactions or, at higher
concentrations, inducing local but also systemic immune depression,
ultimately implicating skin cancero-genesis.
Qualitative modifications of SSL represent a pathogenetic sign of diagnostic
value in dermatological disorders involving altered sebum production, like
pytiriasis versicolor, acne, atopic or seborrheic dermatitis, as well as
photo-aging.
Achievements of nutriceutical interventions aimed at restoring normal SSL
composition & homeostasis are discussed, as feasible therapeutic goals &
major means of photo-protection.
____
Š Among cutaneous SSL components, squalene is a most intriguing component.
SQ represents indeed the most abundant peroxidable fraction in SSL ...
Š all these results confirm earlier classification of SQ as a sacrificial
anti-oxidant, being extensively degraded under different types of peroxidant
stimuli, and very prone to photo-decomposition.
This way, this unique molecule is able to afford protection of human skin
surface from further damage to the lipid mantel & to cellular peroxidable
targets of the viable layers, induced by the exposure to UV etc.
Š
In conclusion, though, from the biological point of view, the reason why SQ
occurs in high concentration in human SSL is still considered an enigma.
On the basis of all described biochemical properties, it can be sensibly
hypothesized that the natural deficiency of SQ oxidocyclase activity in
human sebaceous glands represents an evolutionary advantage:
SQ is capable of neutralizing reactive oxygen species induced by UV
irradiation on the skin, thus behaving as an anti-oxidant and, indirectly
(SQ does not absorb in the UV range), as a natural sun-screen.
The skin of monkeys is covered by a large quantity of hair, protecting from
UV rays.
In the human skin, the shield function is reasonably carried out by SQ, in
ass.x the physical defences of stratum corneum & melanin.
In contrast to human sebum, SSL of other hominidae contains higher levels of
cholesterol, and surprisingly no SQ at all.
Our group has proved that SQ is unique to human sebum, and completely
missing in the main genera of non-human primates, including the hominoidea.
Human sebum also contains
- more TGs & their hydrolysis products &
- far less cholesterol.
SQ terpene typical of human sebum is also a principal surface lipid of
different aquatic mammals: otter, beaver, kinkajou & at least one species of
mole.
In these spp, SQ accounts for the essential properties of water repellence &
thermal insulation.
Other non-aquatic mammals or birds have evolved different cutaneous fats
(eg, wax esters & wax di-esters) ensuring the same vital properties.
The relevant distance of human sebum in composition & function from the
nearest primates, and the close similarity with semi-aquatic mammals, bears
interesting evolutionary implications andmay offer some support to the
discussed hypothesis of the origin of man from some semi-aquatic hominids,
feeding on fish.
Marine food (esp.micro-algae & seaweeds) & edible seeds of plants dwelling
in Mangrovian habitats (eg, Amarantus) display an unusual rich SQ content.
In the light of the AAT, that evidences features of convergence among
different semi-aquatic spp, such as proboscis monkeys, beavers, sea-otters,
hippos, seals, sea lions & walruses, these new biochemical data on human
sebum SQ offer indeed new space for speculation.
Hindawi Publishing Corporation
Mediators of Inflammation Article ID 321494 11pp
doi 10.1155/2010/321494
Review Article
Surface Lipids as Multifunctional Mediators of Skin Responses to
Environmental Stimuli
Chiara De Luca & Giuseppe Valacchi 2010
Philip W Wertz ed
open access
Skin surface lipid (SSL) film is a mixture of sebum & keratinocyte membrane
lipids, protecting skin from environment.
Its composition is unique for the high % of
- long-chain fatty acids (FAs) &
- the poly-terpenoid squalene (SQ), absent in other human tissues & in
non-human Primates sebum.
Here, the still incomplete body of information on SSL as mediators of
external chemical, physical & microbial signals & stressors is revised.
We focus on the central event of the continuous oxidative modification
induced by the metabolic activity of
- residential & pathological microbial flora,
- natural or iatrogenic UV irradiation,
- exposure to chemicals & cosmetics.
Once alpha-tocopherol & ubiquinol-10 anti-oxidant defences of SSL are
overcome, oxidation of SQ & cholesterol gives rise to reactive by-products
penetrating deeper into skin layers, to mediate local defensive
inflammatory, photo-protective, immune reactions or, at higher
concentrations, inducing local but also systemic immune depression,
ultimately implicating skin cancero-genesis.
Qualitative modifications of SSL represent a pathogenetic sign of diagnostic
value in dermatological disorders involving altered sebum production, like
pytiriasis versicolor, acne, atopic or seborrheic dermatitis, as well as
photo-aging.
Achievements of nutriceutical interventions aimed at restoring normal SSL
composition & homeostasis are discussed, as feasible therapeutic goals &
major means of photo-protection.
____
Š Among cutaneous SSL components, squalene is a most intriguing component.
SQ represents indeed the most abundant peroxidable fraction in SSL ...
Š all these results confirm earlier classification of SQ as a sacrificial
anti-oxidant, being extensively degraded under different types of peroxidant
stimuli, and very prone to photo-decomposition.
This way, this unique molecule is able to afford protection of human skin
surface from further damage to the lipid mantel & to cellular peroxidable
targets of the viable layers, induced by the exposure to UV etc.
Š
In conclusion, though, from the biological point of view, the reason why SQ
occurs in high concentration in human SSL is still considered an enigma.
On the basis of all described biochemical properties, it can be sensibly
hypothesized that the natural deficiency of SQ oxidocyclase activity in
human sebaceous glands represents an evolutionary advantage:
SQ is capable of neutralizing reactive oxygen species induced by UV
irradiation on the skin, thus behaving as an anti-oxidant and, indirectly
(SQ does not absorb in the UV range), as a natural sun-screen.
The skin of monkeys is covered by a large quantity of hair, protecting from
UV rays.
In the human skin, the shield function is reasonably carried out by SQ, in
ass.x the physical defences of stratum corneum & melanin.
In contrast to human sebum, SSL of other hominidae contains higher levels of
cholesterol, and surprisingly no SQ at all.
Our group has proved that SQ is unique to human sebum, and completely
missing in the main genera of non-human primates, including the hominoidea.
Human sebum also contains
- more TGs & their hydrolysis products &
- far less cholesterol.
SQ terpene typical of human sebum is also a principal surface lipid of
different aquatic mammals: otter, beaver, kinkajou & at least one species of
mole.
In these spp, SQ accounts for the essential properties of water repellence &
thermal insulation.
Other non-aquatic mammals or birds have evolved different cutaneous fats
(eg, wax esters & wax di-esters) ensuring the same vital properties.
The relevant distance of human sebum in composition & function from the
nearest primates, and the close similarity with semi-aquatic mammals, bears
interesting evolutionary implications andmay offer some support to the
discussed hypothesis of the origin of man from some semi-aquatic hominids,
feeding on fish.
Marine food (esp.micro-algae & seaweeds) & edible seeds of plants dwelling
in Mangrovian habitats (eg, Amarantus) display an unusual rich SQ content.
In the light of the AAT, that evidences features of convergence among
different semi-aquatic spp, such as proboscis monkeys, beavers, sea-otters,
hippos, seals, sea lions & walruses, these new biochemical data on human
sebum SQ offer indeed new space for speculation.
Re: Echolocation & superfast muscles
Superfast Muscles Set Maximum Call Rate in Echolocating Bats
CPH Elemans cs 2011
Science 333:1885-8 doi 10.1126/science.1207309
As an echo-locating bat closes in on a flying insect, it increases call
emission to rates >160 calls/", the "terminal buzz" Š
We found :
- previously unknown & highly specialized super-fast muscles power rapid
call rates in the terminal buzz,
- laryngeal motor performance (not overlap between call production & the
arrival of echoes at the bat's ears) limits maximum call rate.
Superfast muscles are rare in vertebrates, and always associated with extra-ordinary motor demands on acoustic communication
-
Humans can speak very quickly over long periods, including Chinese multi-tonal speech and Khoisan Bushman multi-tonal & variable-click speech, which perhaps produces faster tongue/larynx/velum movements than in monotone languages. Song (hum + lingua-labial variety) can vary speeds also.
Superfast Muscles Set Maximum Call Rate in Echolocating Bats
CPH Elemans cs 2011
Science 333:1885-8 doi 10.1126/science.1207309
As an echo-locating bat closes in on a flying insect, it increases call
emission to rates >160 calls/", the "terminal buzz" Š
We found :
- previously unknown & highly specialized super-fast muscles power rapid
call rates in the terminal buzz,
- laryngeal motor performance (not overlap between call production & the
arrival of echoes at the bat's ears) limits maximum call rate.
Superfast muscles are rare in vertebrates, and always associated with extra-ordinary motor demands on acoustic communication
-
Humans can speak very quickly over long periods, including Chinese multi-tonal speech and Khoisan Bushman multi-tonal & variable-click speech, which perhaps produces faster tongue/larynx/velum movements than in monotone languages. Song (hum + lingua-labial variety) can vary speeds also.
The fascinating part of the hunt occurs when the bat switches to a close in rate and the moth detects it and employs evasive action. Couldn't believe my eyes when I saw the film. A clean kill with the teeth turned into a lucky kick that knocked him into the wing turned brake chute turned net.
Hmm, wondering if yodeling might be echolocational. The extremely brief breaks between vocal notes might allow acoustic echoes to be detected for distance positioning.
Anyone know of any nocturnal (semi-aquatic?) yodelers with big ears in the Alps??
Anyone know of any nocturnal (semi-aquatic?) yodelers with big ears in the Alps??
I've been researching the link between the Chromosome 2 inversion/fusion (which activated the photic sneeze reflex) in humans as opposed to other hominoids (apes). The ARC theory includes the possibility that this Chr.2 inversion enabled improved submerged dive-foraging (faster exhale of "used" air while backfloating under sunlit sky) after about 5,000,000 years ago. A significant addendum to this functional mutation is the change from arboreal bowl-like nests to ground-based "inside out bowl" dome huts. Apes insert leaves into their nests for comfort, indigeonous forest people (eg. Mbuti, Mbarbarm) insert leaves onto the outside of their dome huts, in a coiled shingle fashion, to waterproof the huts. I speculate that long ago, the salt trade was initiated by coastal people that gathered salty mangrove leaves, notched them and hung them from kelp belts, bringing them inland for huts and trade.
I consider the shingled inverted dome-bowl huts to be specifically human, and likely related to the Chrom. 2 inversion, and I think it affected human evolution. Please see this article for the effects of entering a room:
"Radvansky found that the subjects forgot more after walking through a doorway compared to moving the same distance across a room, suggesting that the doorway or "event boundary" impedes one's ability to retrieve thoughts or decisions made in a different room".
Walking through doorways causes forgetting, new research shows
Interesting that entering through a doorway affects the mind. Humans are the only hominioids whose night-time boundaries exclude the sky (great apes sleep in bowl nests above forest floor). (link to submerging into water?)
I think "entering" is part of what made us human, as opposed to hopping into or climbing into a nest.
Words that mean "Inside", interior or in the hut:
West Africa Yoruba: inu
Congo Mbuti: endu/ra
Ethiopian Amharic: indani
Ancient Greek: endo/r
Spanish/Latin: at/ento (tent?)
German: immer (room is zimmer)
Sri Lanka Singhalese: daram (tent = kudaram)
Malay/Indonesian: dalam (tent = kemah)
English: entry/enter/interior/end/inside
DDeden
I consider the shingled inverted dome-bowl huts to be specifically human, and likely related to the Chrom. 2 inversion, and I think it affected human evolution. Please see this article for the effects of entering a room:
"Radvansky found that the subjects forgot more after walking through a doorway compared to moving the same distance across a room, suggesting that the doorway or "event boundary" impedes one's ability to retrieve thoughts or decisions made in a different room".
Walking through doorways causes forgetting, new research shows
Interesting that entering through a doorway affects the mind. Humans are the only hominioids whose night-time boundaries exclude the sky (great apes sleep in bowl nests above forest floor). (link to submerging into water?)
I think "entering" is part of what made us human, as opposed to hopping into or climbing into a nest.
Words that mean "Inside", interior or in the hut:
West Africa Yoruba: inu
Congo Mbuti: endu/ra
Ethiopian Amharic: indani
Ancient Greek: endo/r
Spanish/Latin: at/ento (tent?)
German: immer (room is zimmer)
Sri Lanka Singhalese: daram (tent = kudaram)
Malay/Indonesian: dalam (tent = kemah)
English: entry/enter/interior/end/inside
DDeden
Primate communication in the pure ultrasound
MA Ramsier cs 2012 Biol Letters
Few mammals ‹ cetaceans, domestic cats & select bats & rodents ‹ can send & receive vocal signals contained within the ultrasonic domain, or pure
ultrasound (>20 kHz). [High pitched vocalizations like bats, dolphins]
Here, we use the auditory brain-stem response (ABR) method to demonstrate
that a species of nocturnal primate, the Philippine tarsier Tarsius
syrichta, has a high-frequency limit of auditory sensitivity of c 91 kHz.
We also recorded a vocalization with a dominant frequency of 70 kHz.
Such values are among the highest recorded for any terrestrial mammal, and a
rel.extreme example of US communication.
For Philippine tarsiers, US vocalizations might represent a private channel
of communication that subverts detection by predators, prey & competitors,
enhances energetic efficiency, or improves detection against low-frequency
background noise.
______
Tarsiers Communicate in Secret Speech
Daniel Strain 7.2.12
Can you hear me? Philippine tarsiers are big-eyed but lack many adaptations
to see at night; they may use their ears to hunt for insects.
Meet the world's tiniest cryptographers. Philippine tarsiers (Tarsius
syrichta), primates native to SE.Asia that are often no bigger than a human
hand, pass messages using an unbreakable code: ultrasonic sounds.
A new study shows that these tree-dwellers emit squeaky calls well above the vocal range of any known monkey or ape, perhaps to dodge eaves-dropping predators.
Like any good code, US works because it's rarely used. Few land mammals
(bats & kittens are exceptions) coo or call at frequencies above the normal
range of human hearing, c 20 kHz.
That's largely because US waves, unlike other sound waves, spread out
quickly; that makes it harder for animals to pinpoint the locations of
faraway calls, says study co-author Marissa Ramsier (anthrop.Humboldt SU
Arcata California, Biology Letters).
The first clue that tarsiers use US came from observing an odd behavior. The
big-eyed nocturnal creatures occasionally open their mouths as if ready to
shout, but no sound humans can hear comes out.
On a whim, co-author Sharon Gursky-Doyen (biol.anthrop.Texas A&M University
College Station) brought a microphone used for recording bat chirps to a
Philippine jungle frequented by the primates.
The animals, it turns out, are boisterous ‹ just not to human ears:
"Philippine tarsiers have often been described as quiet. But they're
screaming and talking away, and we just didn't know it."
To dig deeper into tarsier communication, Ramsier cs trapped & sedated 6
tarsiers in the wild.
Using a technique first employed to test hearing in newborn babies, they
monitored the brainwaves of the dozing creatures as noises played on a
speaker. The primates could register sounds up to 90 kHz (slowed down in the
accompanying audio), double the upper limit of any primate studied to date.
The team also listened in on the nighttime back & forth between tarsiers.
Their calls closely resembled the vocalizations of similar primates:
dominated by a single tone followed by several trills.
Except they were much higher, fluctuating around 70 kHz.
Tarsiers use their savvy for hearing & speaking in US to eat & to keep from
being eaten, Ramsier suggests.
The primates dine exclusively on small insects such as moths & katydids,
which also frequently communicate in ultra-high frequencies.
Because tarsiers' perky ears are so sensitive, they may be able to intercept
this chatter at night ‹ then zoom in for the kill.
But they may just as much want to avoid being eavesdropped on. Their
nails-on-a-chalkboard trills are too high-pitched for predators such as
birds to notice, letting mothers & infants talk without drawing the
attention of the entire forest.
Ramsier thinks that hidden communication may be more common than many
researchers suspect.
Scientists, she says, rarely think to listen for US noise:
"I want everyone to go out with their bat detectors."
"It's a neat paper," says Mark Coleman, who studies primate hearing at
Midwestern University in Glendale, Arizona.
But he's not convinced that US communication is so underappreciated in
primates. Based on the shapes of their inner ears, early mammals likely vocalized a lot using US frequencies, the better to hide from hungry dinosaurs, he suggests. [US would also help to hear beetle larvae inside wood, the Madagascar Ayeaye lemur listens while finger-tapping wood, using US for echolocation]
Tarsiers, unlike most other primates, may be one of the few spp to have
retained this ability:
"They're kind of a holdover from this really ancestral mammal ... where
high-frequency communication was the norm."
MA Ramsier cs 2012 Biol Letters
Few mammals ‹ cetaceans, domestic cats & select bats & rodents ‹ can send & receive vocal signals contained within the ultrasonic domain, or pure
ultrasound (>20 kHz). [High pitched vocalizations like bats, dolphins]
Here, we use the auditory brain-stem response (ABR) method to demonstrate
that a species of nocturnal primate, the Philippine tarsier Tarsius
syrichta, has a high-frequency limit of auditory sensitivity of c 91 kHz.
We also recorded a vocalization with a dominant frequency of 70 kHz.
Such values are among the highest recorded for any terrestrial mammal, and a
rel.extreme example of US communication.
For Philippine tarsiers, US vocalizations might represent a private channel
of communication that subverts detection by predators, prey & competitors,
enhances energetic efficiency, or improves detection against low-frequency
background noise.
______
Tarsiers Communicate in Secret Speech
Daniel Strain 7.2.12
Can you hear me? Philippine tarsiers are big-eyed but lack many adaptations
to see at night; they may use their ears to hunt for insects.
Meet the world's tiniest cryptographers. Philippine tarsiers (Tarsius
syrichta), primates native to SE.Asia that are often no bigger than a human
hand, pass messages using an unbreakable code: ultrasonic sounds.
A new study shows that these tree-dwellers emit squeaky calls well above the vocal range of any known monkey or ape, perhaps to dodge eaves-dropping predators.
Like any good code, US works because it's rarely used. Few land mammals
(bats & kittens are exceptions) coo or call at frequencies above the normal
range of human hearing, c 20 kHz.
That's largely because US waves, unlike other sound waves, spread out
quickly; that makes it harder for animals to pinpoint the locations of
faraway calls, says study co-author Marissa Ramsier (anthrop.Humboldt SU
Arcata California, Biology Letters).
The first clue that tarsiers use US came from observing an odd behavior. The
big-eyed nocturnal creatures occasionally open their mouths as if ready to
shout, but no sound humans can hear comes out.
On a whim, co-author Sharon Gursky-Doyen (biol.anthrop.Texas A&M University
College Station) brought a microphone used for recording bat chirps to a
Philippine jungle frequented by the primates.
The animals, it turns out, are boisterous ‹ just not to human ears:
"Philippine tarsiers have often been described as quiet. But they're
screaming and talking away, and we just didn't know it."
To dig deeper into tarsier communication, Ramsier cs trapped & sedated 6
tarsiers in the wild.
Using a technique first employed to test hearing in newborn babies, they
monitored the brainwaves of the dozing creatures as noises played on a
speaker. The primates could register sounds up to 90 kHz (slowed down in the
accompanying audio), double the upper limit of any primate studied to date.
The team also listened in on the nighttime back & forth between tarsiers.
Their calls closely resembled the vocalizations of similar primates:
dominated by a single tone followed by several trills.
Except they were much higher, fluctuating around 70 kHz.
Tarsiers use their savvy for hearing & speaking in US to eat & to keep from
being eaten, Ramsier suggests.
The primates dine exclusively on small insects such as moths & katydids,
which also frequently communicate in ultra-high frequencies.
Because tarsiers' perky ears are so sensitive, they may be able to intercept
this chatter at night ‹ then zoom in for the kill.
But they may just as much want to avoid being eavesdropped on. Their
nails-on-a-chalkboard trills are too high-pitched for predators such as
birds to notice, letting mothers & infants talk without drawing the
attention of the entire forest.
Ramsier thinks that hidden communication may be more common than many
researchers suspect.
Scientists, she says, rarely think to listen for US noise:
"I want everyone to go out with their bat detectors."
"It's a neat paper," says Mark Coleman, who studies primate hearing at
Midwestern University in Glendale, Arizona.
But he's not convinced that US communication is so underappreciated in
primates. Based on the shapes of their inner ears, early mammals likely vocalized a lot using US frequencies, the better to hide from hungry dinosaurs, he suggests. [US would also help to hear beetle larvae inside wood, the Madagascar Ayeaye lemur listens while finger-tapping wood, using US for echolocation]
Tarsiers, unlike most other primates, may be one of the few spp to have
retained this ability:
"They're kind of a holdover from this really ancestral mammal ... where
high-frequency communication was the norm."
Not that I sign for any relation of echolocation and the aquatic ape theory, but I fell on this rather interesting article:
Men’s Journal » The Blind Man Who Taught Himself To See » Print
David, you should ask the guy to learn freediving and try echolocating under water
Men’s Journal » The Blind Man Who Taught Himself To See » Print
David, you should ask the guy to learn freediving and try echolocating under water
A Little Gorilla in Us All - ScienceNOW
In the gorilla, one of the faster-evolving genes is involved in the hardening of skin, as happens in the knuckle pads for knuckle walking.
[Human ancestors never knucklewalked, gorillas and chimps both knucklewalk but do so uniquely; kneecrawling in human infants may be very ancient, related to both sandy shore quadrupedal shallow wading and swimming, and dome hut enclosure impoundment while mothers were foraging, but human infants don't have thick knee skin, indicating that kneecrawling wasn't done regularly outside on rough/hard soils. dd]
Hearing genes that have evolved rapidly in humans also show accelerated evolution in gorillas. Some researchers had thought that those human genes might partly underlie language evolution, but that idea will need some rethinking now, Scally says.
[This is unexpected, I can't explain it. It is possible that body size increase may correlate with change in hearing dynamics (eg. elephants hear normal pitch sounds through their ears and and infrasonic (bass) sounds through bone conduction of their dense leg bones via the ground. Both humans and gorillas are more ground-based than other apes, so it is reasonable speculation, but unconfirmed. Human, gorilla and elephant ancestors spent significant time in water, chimp, orangutan and hyraxes do not. dd]
The researchers also saw parallel acceleration in the evolution of genes for brain development in gorillas and humans.
[Again this may relate to more time spent both on ground and in water foraging for diverse foods (sedge pith/leaves/rhyzomes, shellfish-crustaceans, ground tubers, larvae, waterfowl eggs, floating frogbit/lilies, ground herb/shrub + tree leaves & fruit), as compared to more restricted foraging in the forest canopy (leaves, fruit) as gibbons & orangutans do. dd]
In the gorilla, one of the faster-evolving genes is involved in the hardening of skin, as happens in the knuckle pads for knuckle walking.
[Human ancestors never knucklewalked, gorillas and chimps both knucklewalk but do so uniquely; kneecrawling in human infants may be very ancient, related to both sandy shore quadrupedal shallow wading and swimming, and dome hut enclosure impoundment while mothers were foraging, but human infants don't have thick knee skin, indicating that kneecrawling wasn't done regularly outside on rough/hard soils. dd]
Hearing genes that have evolved rapidly in humans also show accelerated evolution in gorillas. Some researchers had thought that those human genes might partly underlie language evolution, but that idea will need some rethinking now, Scally says.
[This is unexpected, I can't explain it. It is possible that body size increase may correlate with change in hearing dynamics (eg. elephants hear normal pitch sounds through their ears and and infrasonic (bass) sounds through bone conduction of their dense leg bones via the ground. Both humans and gorillas are more ground-based than other apes, so it is reasonable speculation, but unconfirmed. Human, gorilla and elephant ancestors spent significant time in water, chimp, orangutan and hyraxes do not. dd]
The researchers also saw parallel acceleration in the evolution of genes for brain development in gorillas and humans.
[Again this may relate to more time spent both on ground and in water foraging for diverse foods (sedge pith/leaves/rhyzomes, shellfish-crustaceans, ground tubers, larvae, waterfowl eggs, floating frogbit/lilies, ground herb/shrub + tree leaves & fruit), as compared to more restricted foraging in the forest canopy (leaves, fruit) as gibbons & orangutans do. dd]
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