Marc Verha
Sun, Mar-30-08, 17:17
Op 30-03-2008 13:05, m3dodds <dons3148@yahoo.co.uk> schreef:
>>>> AATers say that large brain, breathhold skills,
>>>> plantigrade feet, aligned body form, furlessness, SC fat
>>>> etc.etc. prove that AAT is correct, but anti-AATers say
>>>> that since all these features are seen in humans today,
>>>> and since modern humans are not (semi)aquatic, these
>>>> features do not prove AAT. This is serious objection IMO,
>>>> which is diffucult to answer.
>>> Would tend to disagree (it is not difficult) ... only the
>>> first counts, the remainder are secondary (best left to
>>> AATers ... to tie themselves in knots questioning).
>>> Whereas the first is clear evidence for our waterside
>>> past. The onus is now on AATers to come up with an answer
>>> as to how a primate evolved a large brain and mastered
>>> iodine deficiency on the savanna (or wherever away from
>>> the shore, they think it happened ...)
>> Well,
>> 1) savanna believers will say: there are humans with large
>> brain & iodine needs who run after kudus, so large
>> brains & high iodine needs don't contradict the savanna
>> theory,
>> 2) if AAT is wrong, that doesn't automatically prove the
>> savanna theory: other scenarios are also theoreticallly
>> also possible.
> Yes. There are humans today with large brains and iodine
> needs, who do run after kudus on the savanna, but they too
> are the descendants of a waterside precursor.
In your fantasy, the savanna believers say.
> As said the onus is on anti-AATers to prove the waterside
> hypotheses wrong, explain why a large primate on the open
> plains is the exception in the animal kingdom, in evolving a
> relatively large brain in what for all intents and purposes
> is a desert devoid of the `brain' nutrients easily found on
> the shore.
Yes, but they say: Maasai have large brains & live in
the savanna: no reason why oour ancestors could not have
done that.
> Medical study after study has proven the human brain fares
> better (thrives), on a diet that has marine component
> (seaweeds, shellfish and fish).
Likely, but Maasai still live in the savanna, and fossil
hominid bones are found next to ostrich eggs & traces of
butering of bovid bones.
...
> [3]
>>>> But what if these features are evolving & adapting to our
>>>> present lifestyle? We have to explain why these features
>>>> are *still* present in humans today. We can always
>>>> answer: evolutonary inertia: our semi-aq. past was so
>>>> recent that we haven't had the time to get rid of these
>>>> ill-adapted features.
>>> Only a valid answer if you see 2 to 3 Ma, as being recent.
>> Only 1 generatioàn of ill-adaptedness is enough to
>> eliminate a feature. Evolution can in some circumstances be
>> extremely fast.
> Our waterside past, the significant period of time spent
> foraging on the shore and in shallow water ... probably lies
> several million years in the past (two million + mya?).
Not sure, but I don't think so: the Dmanisi fossils had still
some arm-hanging features.
I guess, after the H/P split c.5 Ma, H colonised the Indian
Ocean shores, at first coastal forests, only later (Ice Ages?
lower sea levels? vaste continetnal shelves + shellfish??)
also tree-poor coasts.
IOW, our ancestors' littoral phase was wholly Pleistocene:
from the coasts their relatives ventured inland along the
rivers, esp.with high sea levels (eg, 1.8 Ma, 1.0 Ma).
> [4]
>>>> But how fast evolution works is a matter of contention.
>>>> Perhaps this is a better answer: all these
>>>> ex(semi)aquatic features seem to have elicited secondary
>>>> adaptations that have countered them *after* we became
>>>> wholly terrestrial again, eg,
>>> Only an valid answer, if our shore ancestors were
>>> semi-aquatic/aquatic, which is unlikely.
>> Not sure what you mean, m3d: shore ancestors not being
>> semi-aquatic??
> Arguing that we are re-adapted terrestrials is an own-goal
> ... (conceding the argument to anti-AATers).
> [5]
>>>> - large brain: our brains are smaller than those of
>>>> neandertals ...
>>> Depends on how big, how robust, how heavily built
>>> your average neanderthal was ... (brain size being
>>> relative ...)
>> Yes, but also Cro-Magnons had larger brains than we today.
> Same answer ... It depends on how robust, heavily built
> Cro-Magnons were in comparison to Modern man (Homo sapiens
> sapiens). Opinion is that Modern man (European) is less
> robust than their Cro-Magnon forefathers.
Yes, possible, uncertain.
> [6]
>>>> - breathhold: unknown how long our ancestors could dive,
>>>> but drownings are not unfrequent in Hs,
>>> Selection could have favoured those capable of holding
>>> their breath longer, even if they were terrestrial ...
>>> occasionally shallow diving to forage.
> [7]
>>>> - plantigrady: fast runners don't run on their soles, but
>>>> on their toes; Hn had broader feet & longer 5th digital
>>>> pedal rays than Hs,
>>> Humans (plantigrade animals) walk ... on the entire foot
>>> (as do bears and rabbits, among others).
>> - rabbits cf.kangaroos = hopping,
>> - bears also ex-semi-aquatic IMO.
> It is a question of how the foot is used, for horses
> (unguligrade) it is life on the tips of the toes, for wolves
> (an birds) it is on the toes (digitigrade) ... humans (an
> bears) use the entire foot (plantigrade).
Yes, but we have to ask: why do horses & cows run on their
hooves? Why cats & dogs on their digits? The faster
(cursorial) the more distantly on the extremities. Humans run
max.30 km/hr or so. Walking we do on our soles, but running
on our toes.
>>>> - aligned body form: not so obvious any more in Hs today,
>>>> - furlessness: some Europeans are have a lot of body fur,
>>>> - SC fat: Africans have only about half the fat of
>>>> Asiatic people (Africans are generally worse swimmers
>>>> than non- Africans): Asians are probably nearer the Hs
>>>> LCA,
> [9]
>>>> - dependency on DHA etc.: Hs has probably a slower growth
>>>> & later puberty than Hn (allowing for more time to get
>>>> enough DHA), - etc.
>>> Not a weakness (dependency) ... But evidence for AAT ...
>> In a certain sense it's a "weakness". In fact, IMO modern
>> land-based Hs need longer maturation periods to collect
>> enough DHA.
> Possibly it is an explanation (the human brain, takes a long
> time to mature - possibly as long as 21 yrs). But, I would
> not see it as a weakness, but as clear evidence ... for the
> waterside hypotheses (AAT).
Well, dry apers will say: Maasai have large brains & are
savanna dwelling.
>>>> In all these case, AATers also have to show that the
>>>> human populations that spend more time in water have what
>>>> AATers think are "(semi)aquatic features":
> [10]
>>>> - do seaside people / fish-eathing people have larger
>>>> brains than other humans?
>>> They may not have a 'larger' brain as such, but the
>>> chances are they'll have one that developed better, works
>>> better than that of there inland kin who suffer from some
>>> form of iodine deficiency ...
> [11]
>>>> - do diving populations (Moken) have longer breath-hold
>>>> skills than, eg, mountain populations? how much of this
>>>> is due to heredity? how much to training?
>>> Probably a combination of both, the longer they spend or
>>> spent in a particular location.
>> Yes.
> [12]
>>>> - plantigrady: do inland populations walk/run more on
>>>> their toes than waterside populations?
>>> Why on Earth, would anyone choose to constantly walk on
>>> their toes? Humans are plantigrade.
>> Cursorial mammals all walk & run on their hooves/toes.
> There are big differences in how species, make use of the
> foot. Some are digitigrade, some unguligrade and others like
> humans are plantigrade. If humans were born to run ... we
> would be digitigrade.
Yes, but we have to ask: why are some spp (bovids, equids)
unguligrade? Why not other spp, eg, ursids, apes?
> [13]
>>>> - are Oceanic islanders more streamlined than, eg, Andean
>>>> highlanders?
>>> No difference, an aligned posture is beneficial to
>>> both ...
>> On land today?? Why? An aligned posture is only
>> advantageous in water AFAIK (hydrodynamism).
> In neither water or on land are humans a 100% aligned, but
> being otherwise relatively aligned is an advantage in and
> out of water ... Think about it, for a moment ... what is
> the easiest way as a biped to carry your weight? Upright?
No, m3d: ostiches & kangaroos carry their weights with
+-horizontal spines.
> [14]
>>>> - we remove our clothes when we go for a swim (then we
>>>> have to assume that fur & clothes have at least partly
>>>> the same functions),
>>> Least we can remove our clothing, being clothed in primate
>>> fur that seldom got a chance to dry would be a real pain
>>> in the butt ... (wet fur, a matted mess ... an home to all
>>> kinds bugs).
> [15]
>>>> - do more cursorial populations (eg, E.Africa) have
>>>> thinner SC fat layers? many long-distance swimmers are
>>>> grossly fat, - etc.
>>> Cursorials are runners ... Humans are plantigrade.
>> Yes, but do, eg, fishing populations have thinner fat
>> layers than hunting populations? > --Marc
> Probably little ... or no difference. Would speculate that
> little has changed in respect to SC fat, since we gained a
> large brain and became relatively hairless. ---m3d
I don't think so: African people have only half our fat :
men have half the fat of women ; Asians are fatter than
Europeans etc.
Note also: fat & fur are independent features:
- some mammals are both: seals...
- some are fat, but furless: dolphins, humans...
- some are lean & furred: most mammals...
- some are lean & furless: elephants, aardvarks, naked
molerats...
--Marc
>>>> AATers say that large brain, breathhold skills,
>>>> plantigrade feet, aligned body form, furlessness, SC fat
>>>> etc.etc. prove that AAT is correct, but anti-AATers say
>>>> that since all these features are seen in humans today,
>>>> and since modern humans are not (semi)aquatic, these
>>>> features do not prove AAT. This is serious objection IMO,
>>>> which is diffucult to answer.
>>> Would tend to disagree (it is not difficult) ... only the
>>> first counts, the remainder are secondary (best left to
>>> AATers ... to tie themselves in knots questioning).
>>> Whereas the first is clear evidence for our waterside
>>> past. The onus is now on AATers to come up with an answer
>>> as to how a primate evolved a large brain and mastered
>>> iodine deficiency on the savanna (or wherever away from
>>> the shore, they think it happened ...)
>> Well,
>> 1) savanna believers will say: there are humans with large
>> brain & iodine needs who run after kudus, so large
>> brains & high iodine needs don't contradict the savanna
>> theory,
>> 2) if AAT is wrong, that doesn't automatically prove the
>> savanna theory: other scenarios are also theoreticallly
>> also possible.
> Yes. There are humans today with large brains and iodine
> needs, who do run after kudus on the savanna, but they too
> are the descendants of a waterside precursor.
In your fantasy, the savanna believers say.
> As said the onus is on anti-AATers to prove the waterside
> hypotheses wrong, explain why a large primate on the open
> plains is the exception in the animal kingdom, in evolving a
> relatively large brain in what for all intents and purposes
> is a desert devoid of the `brain' nutrients easily found on
> the shore.
Yes, but they say: Maasai have large brains & live in
the savanna: no reason why oour ancestors could not have
done that.
> Medical study after study has proven the human brain fares
> better (thrives), on a diet that has marine component
> (seaweeds, shellfish and fish).
Likely, but Maasai still live in the savanna, and fossil
hominid bones are found next to ostrich eggs & traces of
butering of bovid bones.
...
> [3]
>>>> But what if these features are evolving & adapting to our
>>>> present lifestyle? We have to explain why these features
>>>> are *still* present in humans today. We can always
>>>> answer: evolutonary inertia: our semi-aq. past was so
>>>> recent that we haven't had the time to get rid of these
>>>> ill-adapted features.
>>> Only a valid answer if you see 2 to 3 Ma, as being recent.
>> Only 1 generatioàn of ill-adaptedness is enough to
>> eliminate a feature. Evolution can in some circumstances be
>> extremely fast.
> Our waterside past, the significant period of time spent
> foraging on the shore and in shallow water ... probably lies
> several million years in the past (two million + mya?).
Not sure, but I don't think so: the Dmanisi fossils had still
some arm-hanging features.
I guess, after the H/P split c.5 Ma, H colonised the Indian
Ocean shores, at first coastal forests, only later (Ice Ages?
lower sea levels? vaste continetnal shelves + shellfish??)
also tree-poor coasts.
IOW, our ancestors' littoral phase was wholly Pleistocene:
from the coasts their relatives ventured inland along the
rivers, esp.with high sea levels (eg, 1.8 Ma, 1.0 Ma).
> [4]
>>>> But how fast evolution works is a matter of contention.
>>>> Perhaps this is a better answer: all these
>>>> ex(semi)aquatic features seem to have elicited secondary
>>>> adaptations that have countered them *after* we became
>>>> wholly terrestrial again, eg,
>>> Only an valid answer, if our shore ancestors were
>>> semi-aquatic/aquatic, which is unlikely.
>> Not sure what you mean, m3d: shore ancestors not being
>> semi-aquatic??
> Arguing that we are re-adapted terrestrials is an own-goal
> ... (conceding the argument to anti-AATers).
> [5]
>>>> - large brain: our brains are smaller than those of
>>>> neandertals ...
>>> Depends on how big, how robust, how heavily built
>>> your average neanderthal was ... (brain size being
>>> relative ...)
>> Yes, but also Cro-Magnons had larger brains than we today.
> Same answer ... It depends on how robust, heavily built
> Cro-Magnons were in comparison to Modern man (Homo sapiens
> sapiens). Opinion is that Modern man (European) is less
> robust than their Cro-Magnon forefathers.
Yes, possible, uncertain.
> [6]
>>>> - breathhold: unknown how long our ancestors could dive,
>>>> but drownings are not unfrequent in Hs,
>>> Selection could have favoured those capable of holding
>>> their breath longer, even if they were terrestrial ...
>>> occasionally shallow diving to forage.
> [7]
>>>> - plantigrady: fast runners don't run on their soles, but
>>>> on their toes; Hn had broader feet & longer 5th digital
>>>> pedal rays than Hs,
>>> Humans (plantigrade animals) walk ... on the entire foot
>>> (as do bears and rabbits, among others).
>> - rabbits cf.kangaroos = hopping,
>> - bears also ex-semi-aquatic IMO.
> It is a question of how the foot is used, for horses
> (unguligrade) it is life on the tips of the toes, for wolves
> (an birds) it is on the toes (digitigrade) ... humans (an
> bears) use the entire foot (plantigrade).
Yes, but we have to ask: why do horses & cows run on their
hooves? Why cats & dogs on their digits? The faster
(cursorial) the more distantly on the extremities. Humans run
max.30 km/hr or so. Walking we do on our soles, but running
on our toes.
>>>> - aligned body form: not so obvious any more in Hs today,
>>>> - furlessness: some Europeans are have a lot of body fur,
>>>> - SC fat: Africans have only about half the fat of
>>>> Asiatic people (Africans are generally worse swimmers
>>>> than non- Africans): Asians are probably nearer the Hs
>>>> LCA,
> [9]
>>>> - dependency on DHA etc.: Hs has probably a slower growth
>>>> & later puberty than Hn (allowing for more time to get
>>>> enough DHA), - etc.
>>> Not a weakness (dependency) ... But evidence for AAT ...
>> In a certain sense it's a "weakness". In fact, IMO modern
>> land-based Hs need longer maturation periods to collect
>> enough DHA.
> Possibly it is an explanation (the human brain, takes a long
> time to mature - possibly as long as 21 yrs). But, I would
> not see it as a weakness, but as clear evidence ... for the
> waterside hypotheses (AAT).
Well, dry apers will say: Maasai have large brains & are
savanna dwelling.
>>>> In all these case, AATers also have to show that the
>>>> human populations that spend more time in water have what
>>>> AATers think are "(semi)aquatic features":
> [10]
>>>> - do seaside people / fish-eathing people have larger
>>>> brains than other humans?
>>> They may not have a 'larger' brain as such, but the
>>> chances are they'll have one that developed better, works
>>> better than that of there inland kin who suffer from some
>>> form of iodine deficiency ...
> [11]
>>>> - do diving populations (Moken) have longer breath-hold
>>>> skills than, eg, mountain populations? how much of this
>>>> is due to heredity? how much to training?
>>> Probably a combination of both, the longer they spend or
>>> spent in a particular location.
>> Yes.
> [12]
>>>> - plantigrady: do inland populations walk/run more on
>>>> their toes than waterside populations?
>>> Why on Earth, would anyone choose to constantly walk on
>>> their toes? Humans are plantigrade.
>> Cursorial mammals all walk & run on their hooves/toes.
> There are big differences in how species, make use of the
> foot. Some are digitigrade, some unguligrade and others like
> humans are plantigrade. If humans were born to run ... we
> would be digitigrade.
Yes, but we have to ask: why are some spp (bovids, equids)
unguligrade? Why not other spp, eg, ursids, apes?
> [13]
>>>> - are Oceanic islanders more streamlined than, eg, Andean
>>>> highlanders?
>>> No difference, an aligned posture is beneficial to
>>> both ...
>> On land today?? Why? An aligned posture is only
>> advantageous in water AFAIK (hydrodynamism).
> In neither water or on land are humans a 100% aligned, but
> being otherwise relatively aligned is an advantage in and
> out of water ... Think about it, for a moment ... what is
> the easiest way as a biped to carry your weight? Upright?
No, m3d: ostiches & kangaroos carry their weights with
+-horizontal spines.
> [14]
>>>> - we remove our clothes when we go for a swim (then we
>>>> have to assume that fur & clothes have at least partly
>>>> the same functions),
>>> Least we can remove our clothing, being clothed in primate
>>> fur that seldom got a chance to dry would be a real pain
>>> in the butt ... (wet fur, a matted mess ... an home to all
>>> kinds bugs).
> [15]
>>>> - do more cursorial populations (eg, E.Africa) have
>>>> thinner SC fat layers? many long-distance swimmers are
>>>> grossly fat, - etc.
>>> Cursorials are runners ... Humans are plantigrade.
>> Yes, but do, eg, fishing populations have thinner fat
>> layers than hunting populations? > --Marc
> Probably little ... or no difference. Would speculate that
> little has changed in respect to SC fat, since we gained a
> large brain and became relatively hairless. ---m3d
I don't think so: African people have only half our fat :
men have half the fat of women ; Asians are fatter than
Europeans etc.
Note also: fat & fur are independent features:
- some mammals are both: seals...
- some are fat, but furless: dolphins, humans...
- some are lean & furred: most mammals...
- some are lean & furless: elephants, aardvarks, naked
molerats...
--Marc