From Newsgroup: talk.origins
On 8/26/2025 7:45 AM, Ernest Major wrote:
On 26/08/2025 09:36, Martin Harran wrote:
All animals seem to be born with some level of innate knowledge;-a a
newborn mammalian child knows how to suckle its mother's teat; a
newborn pup knows to yelp to attract its mother's attention; a
squirrel knows to store nuts for the winter.
It seems obvious that such knowledge is stored within our DNA but has
research into the human genome come up with anything at all to
indicate where or how it is actually stored?
To restate the well-known, a recipe is a better analogy for a genome
than a blueprint. Looking for a specific location ("where") in the
genome for the encoding of behaviour is a mistake.
The general answer is that organisation of the nervous is controlled by
the interaction of various parts of the genome (and to various degrees
the environment), and in some cases behaviours are inherent in that organisation.
For humans this is nigh on impossible to answer because of the
complexity of the system. You can ask simpler questions, such as
behaviour in Caenorhabditis elegans, which has a small number of neurons with deterministic development, or how the processing of sensory data is controlled by the genome. At the extreme you could look at chemotaxis in bacteria, where one can look at how the interaction of a G protein
coupled receptor with a small molecule sets of a chain of protein interactions that result in physical movement of the bacterium.
I don't seen any obvious reason why things would be different in single- celled eukaryotes, though one might reasonably expect larger repertoires
and greater sophistication of behaviour. Moving to multicellular
organisms intercellular signalling adds another layer of complexity, and
in animals there's an additional layer of neuronal signalling.
But perhaps I overstate the difficulty in asking questions about humans.
The patellar reflex is found in a number of mammals including humans. A relative short chain of neurons connects the sensory input to the reflex motor movement, reducing the question to how is that arrangement of
neurons represented in the genome. A somewhat more complicated system is represented by the diving reflex.
There was just a thread on consciousness. Consciousness seems to be the ability to remember the cause of the physical stimuli that evoked the behavioral response. Consciousness allows us to learn from physical
stimuli and develop behaviors. Innate behaviors are literally knee jerk reactions to the environment. Touching a newborn babies cheek and it
will turn to suckle, and stroking the bottom of a newborn's feet to
watch them curl (grasping reflex, likely, from when ancestral arboreal newborns had grasping feet). If a baby doesn't perform these behaviors
at birth there is usually something neurologically wrong. Something is
messed up between the stimuli and the neurological signalling that is
required to perform the behavior.
Innate behaviors are just automatic responses to environmental stimuli,
and there isn't any one gene involved in these behaviors. We have
taste, smell, feel, hearing and sight, and we have innate behaviors that
have survival value at unexpected sensory input. Something could be
looking for you or jumping at you. Just like E. coli some of these
senses use G protein coupled receptors to send signals due to
environmental input, and we have sensory neurons.
One thing that I have wanted to try to look at is brooding behavior in
birds. You can hatch a female chick in isolation, but that chick will
still be able to nest, incubate, and brood a batch of chicks. When
mature and the days start to lengthen in Spring a hen will start
nesting. Chickens do not make elaborate nests, just depressions covered
with crude nesting material and some feathers, under some type of cover.
They start laying an egg a day, but only go back to the nest to lay. Something in the hen's brain counts the number of eggs, and when the
number is enough laying stops and incubation begins. The embryos start further development once incubation begins so the eggs all hatch around
the same time. You can keep a wild-type hen laying more than 80 eggs by
just taking away the eggs as they are laid. Otherwise she will start incubating when she has around 8 eggs in the nest. A hen will turn the
eggs every 15 to 20 minutes. She dips her head under her body and rolls
a few eggs each time. She doesn't turn all the eggs every time, and
automated incubators turn the eggs every 1 to 2 hours, and when I got my
first incubator I was able to get decent hatches by just turning the
eggs 3 times a day (when I woke up, after I got home from school, and
before I went to bed). If birds do not turn the eggs the embryos can
get attached to the inner membrane and be damaged if the eggs are
disturbed (mound nesters do not turn their eggs, but incubate like
alligators and turtles so the eggs remain undisturbed in the same orientation). The hen will leave the nest about once a day to drink and
eat until around day 18 of incubation when she somehow senses the chicks
in the eggs and goes into a sort of trance. She stops turning the eggs,
and does not get off the nest. She remains in this trance for up to 72
hours after the first chick hatches on day 21. This gives all the
chicks a chance to hatch and be ready to move off the nest.
Commercial layers have been selected to not go broody. Crosses indicate
that the behavior is disrupted in at least two ways. You can cross two nonbroody lines and produce broody birds, so the defects are independent
and can complement each other. You have to be homozygous for each
defect. Both defects seem to block the start of incubation, so the
birds keep laying eggs. The egg counting mechanism is messed up or the transition to incubation is somehow blocked. I used to have an inbred
Leghorn line that was nonbroody and laid a lot of eggs, but they
retained the nesting behavior and would try to gather eggs underneath
the hen. So they still had that part of the behavior, but for some
reason they never started incubation and kept laying eggs. Some
researchers have gotten the birds to brood chicks so they haven't lost
that ability they just never get to the point of having chicks hatch
under them to stimulate chick brooding behavior.
You have physical stimulation that triggers hormonal changes that result
in altered behavior. The hormonal levels seem to just change a bit, and
it isn't an on and off switch. This seems to be enough to get the brain
to send the next batch of signals.
Ron Okimoto
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