A basic idea underlying the evolutionary approach to cognition is that serious changes in behavior are consequences of alterations in the genome. However, this assumption is wrong for our species. Indeed, the children of hunter-gatherers and farmers may become stock brokers and coders simply because farming was a standard occupation for one generation and coding is a typical occupation for the following generation. If our species is so flexible then it is reasonable to assume our ancestors were very adaptive too and able to adjust phenotypically to any situations. Then why after the emergence of bipedalism human evolution took place? Such answers as because only our species has some unique characteristics (language, etc.) do not seem interesting.
I see no contradiction: The cognition of the earliest biped hominids was different from, probably inferior to, that of the later Homo sapiens. So our older ancestors might have been less flexible/versatile than our younger ancestors. Versatility can be regarded as a "metacharacteristic" of human beings which has evolved as well: With some exceptions (Homo florensis?) it increased during human evolution.
I confess that I don't follow your logic at all, but this seems like another iteration of the absurd claim that humans are somehow so special that evolution does not apply to us.
Some of the "adaptive" ability that you discuss is occupational (a strange concept from a biological perspective and by definition incomparable to other animals, right?), and then you somehow relate this adaptability to the key evolutionary landmark of bipedality - another weird choice; what do knees and feet, etc. have to do with the ability to be a stock broker or coder. Again, I apologize for not really understanding the question.
You claim that the idea that "serious changes in behavior are consequences of alterations in the genome" is "wrong for our species". I see no evidence to substantiate that claim. Why isn't our adaptability a genetic alteration that has evolved?
Furthermore, though you seem to think that the only type of human evolution must be cognitive (i.e., your title discusses human evolution as a whole but your question only discusses cognitive evolution aside from the weird inclusion of bipedality), we clearly may be and probably are still evolving in other parts of our anatomy. For instance, if any problems with our anatomy cause us to modify our decisions about having kids, then those are selection forces. The number of people making decisions based on the same anatomy would dictate the strength of that selection, but even minor trends are valid evolutionary pressures. I have two personal examples of this: one friend decided to adopt a second child rather than have a biological one after his first child was born with Tetralogy of Fallot. They found out that the combination of their genes would result in a very high likelihood that their subsequent biological children would be born with the same condition. If other parents make this same decision, then those genes could be dropped from the gene pool over time.
Even simpler anomalies might have similar evolutionary effects. For instance, another one of my friends has a "bad back" - a clear consequence of our incomplete and imperfect bipedal evolution - and this pain was exacerbated when she had her daughter. She decided not to have another child, in part because of this condition. If other people are making similar decisions about back or neck or knee or ankle, etc., issues, then perhaps many many generations from now our bipedality will be less troublesome. Clearly it causes problems (I've never met someone who doesn't know someone else who has ruptured a disk, blown a knee or hurt an ankle, do you?) and if these problems lead to even minor differences in reproductive decisions, then that is evolution my friend.
To Michael Buchwitz
Yes, I agree that human flexibility might have increased during human evolution. However, it is not clear why this occurred. Indeed, the habitat of ancient humans (i.e. the African savanna) had been practically invariable for millions of years and first Homo equipped with stone tools, fire, and relatively complex language were sufficiently adapted to hunting-gathering in this milieu. They left Africa and effectively developed cold Eurasia. In principle, Homo erectus (Homo ergaster ) could be the final stage in human evolution. I do not understand why this was not the case.
To Adam Hartstone-Rose
First, thank you for your efforts to understand my question and even other texts. I see you attempted to decipher it such as an archeologist tries to decipher an ancient manuscript :)) Of course, I do not think that evolution does not apply to us. I am an absolute proponent of evolution. Undoubtedly, the principles of evolution influence on how humans adapt to changes in the environment. The development of lactose tolerance after the domestication of cows and goat is a good example of the work of evolutionary mechanisms nowadays.
However, except such “blind” mechanism of adaptation, humans have another, cognitive system of adaptation. This system is much more flexible and adaptive. My example with occupations is a presentation of its flexibility. In my opinion, before the emergence of bipedality the standard evolutionary mechanism was the main method of adaptation but after this the cognitive system became dominant. This conclusion is a reflection of the fact that since then our body has changed, in general, weakly, however, our ability to influence the world has changed enormously. A true model of human evolution must effectively explain the interaction between these methods of adaptation. In my opinion, no current models are able to do this.
Pavel, you say "the habitat of ancient humans (i.e. the African savanna) had been practically invariable for millions of years and first Homo equipped with stone tools, fire, and relatively complex language were sufficiently adapted to hunting-gathering in this milieu". These are the usual traditional just-so assumptions: schematically: "early quadrupedal primates lived in the trees; when our ancestors left the forests, they became bipedal runners on savannas". This illogical thinking (post hoc, ergo propter hoc) is wrong, of course, e.g. savanna baboons are more quadrupedal than forest baboons (R.Bender called this the "baboon paradox"). Comparative evidence shows that Pleistocene Homo dispersed intercontinentally along African & Eurasian coasts & rivers (e.g. attachment), not running over open plains (e.g. google "econiche Homo" disproved "endurance running").
Marc, as I understand it, the goal of your post was to try to familiarize me with AAH. I have read the text attached. I absolutely didn’t become a proponent of AAH. On the other hand, I don’t want to criticize AAH because I think no criticism is able to change your mindset.
The baboon paradox may be considered as important only if one suggests that prior to entering the savanna early hominids were practically the same as baboons. However, if these hominids were distinctive (for example, if they were semi-bipedal ) then they could evolve differently and the paradox disappears. The spread along rivers and coasts itself does not mean that early humans were “aquatic”. Possibly, that these routes were more available and convenient, etc.
I think no criticism is able to change *your* mindset, Pavel. You already seem to agree that early-Pleistocene Homo spread along coasts & rivers between the coastal floodplain of Aïn-Hanech in Algeria & the coastal sediments of Mojokerto on Java c 1.8 Ma: there's no way of connecting these sites (& other Homo sites) by running over savannas or so. Humans, although +-fully terrestrial today, are (still) capable of diving for sessorial littoral foods, so there's no reason why our early-Pleistocene ancestors spreading along African & Euraisan coasts would not have dived (parttime) for seafoods (see e.g. the recent papers of José Joordens in JHE etc.).
That they indeed regularly dived (at least during certain evolutionary phases in the Pleistocene) is proven by the pachyosteosclerosis in many Pleistocene Homo specimens (M.Verhaegen & S.Munro 2011 "Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods" HOMO J.compar.hum.Biol.62:237-247). An early-Pleistocene littoral dispersal (beach-combing, wading bipedally & shallow diving) most parsimoniously explains (independently!) several other characters in H.erectus & relatives, e.g. ear exostoses, platycephay, platymeria, platypelloidy, external nose, drastic brain enlargement (DHA) etc.
Mark, all modern great apes have very limited habitats and very limited diets. To leave Africa and to develop Eurasia ancient hominids should have been fundamentally changed all aspects of their living. In my opinion, they acquired bipedality, language, tools, complex joint activity and they became, in general, humans adapted to various conditions. Possibly, that some of such early humans dispersed along rivers and coasts. However, they did not use swimming and diving for getting food simply because this is quite ineffective. Try to catch a fish by hands while swimming. No modern humans do this and I think early humans were smart enough to understand the absurdness of this method of living.
All contemporary hominids are terrestrial and the there have been no reliable data that the situation was different in the past (you directly wrote “AAH is even less about the hominid fossil record”). However, you postulate the existence of an “aquatic” stage. Your main argument is a similarity between some human features and the characteristics of some arbitrarily selected water animals such as frogs and flamingoes. Such argumentation is simply ridiculous because using it practically any hypothesis of human evolution can be supported.
For example, it is possible to imagine another version of AAH, where the first “A” is not “aquatic” but “aerial”. The aerial ape hypothesis does not assume that some ancient hominids flew as birds. The hypothesis suggests that ancient hominids instinctively (beavers instinctively build complex dams) constructed wings from leaves and branches and glided on these wings between trees. This activity made them more bipedal, more intelligent, etc. A (aerial)AH is supported by such similarities: humans are bipedal and birds are bipedal; humans have speech and birds have their songs; humans are, in general, monogamous and birds, in general, are the same, humans have buildings ( artificial constructions) and birds have nests ( artificial constructions), humans are, possibly, intelligent and some birds ( parrots, crows) are very intelligent.
Pavel, apparently you didn't even read the attachment. I summarise, it's not difficult, just pay a bit attention: H.erectus & relatives have several *independent* anatomical indications of a littoral lifestyle incl.shallow diving for shellfish, contradicting cursorial as well as your aerial lifestyles: pachyosteosclerosis, ear exostoses, platycephaly, platymeria, flaring ilia, brain expansion, external nose etc. Coastal & later riverside dispersal is confirmed by all fossil, paleo-environmental & archeological data: early-Pleistocene dispersal between Algeria & Java 1.8 Ma, coastal sites all over the African & Eurasian coasts (England, Med.coasts, Red Sea, Eritrea, Namibia, Cape, Flores etc.), always found amid edible shellfish, traces of shell opening etc., e.g. see the paper of J.Joordens cs in Nature on shellfish consumption by H.erectus (to be released this evening AFAIK).
For José Joordens' paper, google e.g. "joordens erectus nature 2014" or so: about 1.2 mill.yrs ago, H.erectus used shark teeth to open freshwater shells: it was probably a large river not far from the sea. In any case, it confirms that Pleistocene Homo dispersed along the African & Eurasian coasts & rivers rather than running over open plains.
- Badges
- Science topic