Elephant Hair Surprise
Andre Willers
19 Jul 2013
Synopsis :
Elephant hair causes cooling , not warming .
Discussion :
1.Elephants
“Abstract
The idea that low surface densities of hairs could be a heat
loss mechanism is understood in engineering and has been postulated in some
thermal studies of animals. However, its biological implications, both for
thermoregulation as well as for the evolution of epidermal structures, have not
yet been noted. Since early epidermal structures are poorly preserved in the
fossil record, we study modern elephants to infer not only the heat transfer
effect of present-day sparse hair, but also its potential evolutionary origins.
Here we use a combination of theoretical and empirical approaches, and a range
of hair densities determined from photographs, to test whether sparse hairs
increase convective heat loss from elephant skin, thus serving an intentional
evolutionary purpose. Our conclusion is that elephants are covered with hair
that significantly enhances their thermoregulation ability by over 5% under all
scenarios considered, and by up to 23% at low wind speeds where their
thermoregulation needs are greatest. The broader biological significance of
this finding suggests that maintaining a low-density hair cover can be
evolutionary purposeful and beneficial, which is consistent with the fact that
elephants have the greatest need for heat loss of any modern terrestrial animal
because of their high body-volume to skin-surface ratio. Elephant hair is the
first documented example in nature where increasing heat transfer due to a low
hair density covering may be a desirable effect, and therefore raises the
possibility of such a covering for similarly sized animals in the past. This
elephant example dispels the widely-held assumption that in modern endotherms
body hair functions exclusively as an insulator and could therefore be a first
step to resolving the prior paradox of why hair was able to evolve in a world
much warmer than our own.
Citation: Myhrvold CL, Stone HA, Bou-Zeid E (2012) What
Is the Use of Elephant Hair? PLoS ONE 7(10): e47018.
doi:10.1371/journal.pone.0047018”
“ Our work is consistent with findings for leaf hairs[22] and cactus spines [23], [24], whose sparse projections create an effect
analogous to elephant hairs in both cases. It is likely that examples exist for
other present-day biological organisms, particularly plants, which should be
investigated in future work.”
2.Humans
“A new school of research, led by scientists like
University of Utah biologist Dennis Bramble and Harvard University
palaeoanthropologist Daniel Lieberman, suggests that early humans needed rapid
cooling systems like sweat glands and now, perhaps, hair.”
3.Pin fin design
·
Pin fin heat sinks are considered to be among the most powerful
heat sink designs available today
·
Pin fin heat sinks provide very low thermal resistance values
per given space and low pressure drop
·
The cooling capabilities of pin fins stem from the round
geometry of the pins, the omnidirectional pin configuration, and the use of
highly conductive materials
·
The smooth round pins reduce resistance to incoming air streams
and enhance air turbulence between the pins
·
The omnidirectional structure maximizes the entrance of fresh
air into the pin array and at the same time allows the hot air to exhaust from
the pin array in every possible direction
·
The use of highly conductive materials further reduces the
thermal resistance of the heat sinks
·
Cool Innovations has further enhanced the performance of pin fin
heat sinks via the introduction of the splayed and flared pin fin designs
·
Their unique structure allows them to offer lower thermal
resistance values and lower pressure drop per given space
4.Polar bears :
In hot temperatures , there is no insulating
fluff . Only erect pins . The bear is quite capable of handling high
temperatures .
5.Dinosaurs :
Feathers evolved to dump heat . But could
conserve it as well .
6.Flapping of feathers by large dinosaurs in a
hot environment served to cool them . The physics requires only a moderate
relative windspeed .
7.The feathers would be in an erectile state in a
warm environment .
8.A cold period would stimulate flight . The
feathers would close in .
9.Thorns on desert plants :
Not defense , but temperature regulation .
10 .That is why thorny desert plants are not poisonous
, while many tropical plants are .
Wow !
Ever wondered why desert plants are succulent ,
but not poisonous ?
Not high enough density of herbivores to trigger high-cost
formation of poisons . The spines/thorns help against predators , but they eat
them anyway .
Temperature control !
11.Rhino hair
https://en.wikipedia.org/wiki/Rhinoceros
Most of its body
hair is
found on the ear fringes and tail bristles, with the rest distributed rather
sparsely over the rest of the body.
The horn is rather
inferior hair .The bio-active hair are found on the body .
Rhino should be farmed and
shorn like sheep in winter . The body hair contains sildanifil (Viagra) to
erect them in hot weather .
Shorn ostrich feathers
will have the same effect . Probably better . Older .
Ostrich feathers can be
substituted for rhino horn .
12. Crocodile feathers .
A slight genetic tweak and
you can have thousands of tons of compacted crocodile feathers (ie hair) , ie
rhino horn .
Shearing rhino’s and
crocodiles takes real men .
Andre .
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