Re: Savanna nonsense

On 17 Oct 2005 11:30:15 -0700, "JAE" <jae@xxxxxxxxxxx> wrote:

>I think you have to be clearer about what you mean by "nutritional
>deficits." Is it a caloric deficit or a deficit of particular
>nutrients?

I'm talking about an overall caloric deficit, a general shortage of
food, something which affects every species from time to time. If it's
regular and predictable (like winter, or the dry season), the species
will adapt to that. If it's erratic or infrequent, adaptation is less
likely.

Deficiencies of specific nutrients occur when the diet is unbalanced
for some reason, even though there may be plenty of food overall. I
suspect it's largely a post-agricultural phenomenon in humans.

[Snip]
>Putting on fat as a caloric cache is a relatively widespread phenomenon
>in the animal kingdom. The degree with which this happens does appear
>to vary, but the ability to lay down fat isn's something at all unique
>to humans and our closest relatives amongst primates will get fat when
>presented with ample calories as well. The baseline below which things
>start going wrong may be elevated in humans but comparing agricultural
>societies (and post agricultural societies) to wild chimps is clearly
>not a good indicator of what's going on.

Well, yes and no. Here's what Caroline Pond has said on the subject at
various times: "Only cetaceans, pinnipeds and a few species of
carnivores and rodents normally have as much fat as 'typical' humans";
"The average fatness of humans is much greater than that of monkeys";
"More than half the 31 captive monkeys that we examined were less than
5% fat, thinner than most laborotory rodents, although all of them had
continuous access to food and little opportunity to exercise. ... The
minimum fatness recorded for teenage girl athletes is 7%, and for men
5%. Thus most human beings are not only much fatter than most wild and
captive mammals, but women and girls are consistently fatter than men
and boys."

That suggests that modern human fatness is mostly outside the range of
other primates (although I have found it impossible to find good data
on wild great apes or hunter/gatherers). So I don't think it's enough
simply to say - well, other primates get fat too. Humans are different
enough that fat levels do need to be explained.

It would be possible to make the case that human fatness is a modern
phenomenon, deriving from a more settled lifestyle and an abundance of
food, particularly starches, although the gender differences don't
fit, and it seems unlikely that the newborn's 15% fat level results
from overeating.

It would also be possible to make the case that human fatness is
related to reproduction and the needs of the infant, but then it would
be necessary to show what infant fat is actually used for (which isn't
obvious), and that the fat levels of adult males and older children is
actually within primate norms. It also seems inefficient for the
infant to convert energy to fat, and then convert it back later, when
it has a regular food supply from its mother.

And there remains the possibility that human fatness derives from an
aquatic lifestyle, but again, the gender differences don't fit, and
since modern humans are not particularly aquatic, why do we still have
so much fat?

So perhaps the answer is some combination of all of these.

--
Pauline Ross
.

Relevant Pages

  • Re: Savanna nonsense
    ... Is it a caloric deficit or a deficit of particular ... > suspect it's largely a post-agricultural phenomenon in humans. ... >>Putting on fat as a caloric cache is a relatively widespread phenomenon ...
    (sci.anthropology.paleo)
  • Re: Bo Graslund "Early humans & their world" Routledge
    ... >> FYI this is one of my texts on fat: Humans lack the short reflective fur ... > Since early Homo is clearly a savanna mammal, ... just the opposite of the water resistant design of Homo. ...
    (sci.anthropology.paleo)
  • Re: Ape theories & Aquaticism
    ... > the need for buoyancy is greatest. ... the ones with least fat. ... > Well as humans have a very large brain too, which is even more costly, ... species N has a very unusual feature ...
    (sci.anthropology.paleo)
  • Anti-AAT arguments
    ... anti-AATers say that since all these features are ... seen in humans today, ... large brain & iodine needs who run after kudus, ... SC fat: Africans have only about half the fat of Asiatic ...
    (sci.anthropology.paleo)