Re: Bipedalism and theorizing... was Re: Morgan and creationists

John Waters (
16 Sep 1996 00:17:02 GMT

Paul Crowley <> wrote in article

JW: Thank god for the discerning amateur. (If it were not for
the likes
of Paul Crowley and John Hawks, where would we all be?)

> Whenever you see the word "forced" in an evolutionary argument
> hackles should rise.

I don€t know what other word to use here. The agency of force
would be maternal instinct, one of the strongest instincts known
among mammals. The hominid nursing females would feel
compelled by their maternal instincts to carry their dependent
infants from feeding place to feeding place. Those who didn€t,
would not bequeath their genes to the future population gene

> You're saying (a) proto-hominids got smaller

JW: No, not necessarily. The evolutionary pressure for an
improved power to weight ratio tends to lead to a slimmer,
slighter body. There may not be any reduction in height. Indeed,
modern nomadic peoples who walk from place to place, such as
the Kenya Masai and Australian Aborigines, tend to be relatively

> (b) their brains got relatively larger,

JW: The evidence shows that their was no change in the
brain/head/skull size until 2.2 mya. (See previous letter by
Hawks.) The evidence also shows that the hominid skeletal
structure got slimmer and slighter. (Or as the Palaeontologists
put it, there was a change in skeletal structure from the Robust
to the Gracile.)

> (c) this lead to more altricial infants

JW: The quality of helplessness would not increase, simply its
length. Ape infants are altricial until they are weaned. Human
babies are not more altricial than ape infants. The key
lies in the length of total helplessness. Ape infants are
helpless for up to 24 hours. By contrast human infants are
helpless for the first three months of their life.

Perhaps a more important indicator, from an evolutionary point
of view, is the relatively locomotion abilities of Ape and Human
infants beyond the stage of total helplessness. In this regard,
human infants can only match the locomotion behaviour of a
two day old Chimpanzee (Pan Troglodytes), about six or seven
months after its birth.

> which (d) caused bipedalism.

JW: Chimpanzee females who give birth to stillborn young, or
infants stricken with polio, have been observed attempting to
suckle such infants, and likewise attempting to carry their
while moving to a new feeding place. This illustrates the
strength of the maternal instinct.

The hypothesis cannot be proved absolutely, but it must be
considered in relation to known facts, such as those illustrated

> I find this, in itself, a bit hard to accept. You're saying
> smaller mothers with more slowly developing infants would have
> significant advantage over larger females with faster
> It does not sound right. Smaller size can be an advantage,
> more altricial infants? They'd impose great difficulties on
> their mothers at a particularly stressful time. On the face
> it, an infant with an altricial period of one week would have
> much smaller chance of survival than one with a period of a
> You need to be able to specify some very substantial
> advantages.
> Paul.

JW: Compensatory advantages? Paul do you know what you are
saying? Do you realise you are (metaphorically speaking)
treading on a Darwinian sacred cow?

Let us consider the theory. The modern Synthetic Theory of
Evolution says that: evolution proceeds through natural
of heritable differences arising at random in each generation.
The genetic variations are the result of chance transformations,
combinations, divisions and multiplications. Furthermore,
selection would only effect variations of an advantageous or
disadvantageous nature.

There is no room for compensatory advantages here. Either a
variation is wholly advantageous or disadvantageous.

Personally, I do not agree with this. It seems to me to be
perfectly possible to have variations which are both
advantageous and disadvantageous. Natural selection would
then be determined on the basis of whether there was a net
advantage or net disadvantage. But this is an unorthodox
attitude. Only discerning amateurs can be unorthodox.

In respect of your last paragraph Paul, you seem to be unaware
that evolution is usually a very slow process. There would be no
question of small mothers with slowly developing infants
competing directly with larger females who had faster

The early differences in the period of infantile helplessness
would be very small. Perhaps two to four hours. This would not
be enough to render the females concerned uncompetitive.
Furthermore, as the period increased, the hominid mothers
would adapt to the needs of their young. There would be a
consequential increase in infant rearing capability.

Likewise, the advantages accruing as a result of the improved
power to weight ratio would be quite small. In extreme
circumstances, it might give an individual an extra mile of
endurance. But that could be the difference between survival
and death. Only marginal, but this is the way of long term

To sum up Paul, I am (generally) one of those orthodox chaps
who believe you have got to relate any given hypothesis to the
facts. My hypothesis does that.

The facts are that the hominids did become bipedal. There was
a change in their head to body ratio. The change in the head to
body ratio was intitiated at the beginning of hominid
development. There was an increase in the period of total
infantile helplessness. This would necessitate the eventual
carriage of the totally helpless babies. Maternal instinct is
one of
the strongest mammal instincts.

John Waters

John Waters is the author of "Helpless as a Baby",
a book concerned with general and human
evolution. It may be accessed at URL