How scientists perceive the evolutionary origin of human traits:
Results of a survey study
Hanna Tuomisto, Matleena Tuomisto & Jouni T Tuomisto 2018
Ecol. & Evol. doi org/10.1002/ece3.3887 open access

Various hypotheses have been proposed for why the traits distinguishing humans from other primates originally evolved,
and any given trait may have been explained both as an adaptation to different environments & as a result of demands from social organization or sexual selection.
To find out how popular the different explanations are among scientists, we carried out an online survey among authors of recent scientific papers in journals covering relevant fields of science:
paleo anthropology, paleontology, ecology, evolution, human biology.
Some of the hypotheses were clearly more popular among the 1266 respondents than others, but none was universally accepted or rejected.
Even the most popular of the hypotheses were assessed “very likely” by <50% of the respondents,
but many traits had 1–3 hypotheses that were found at least moderately likely by >70% of the respondents.
An ordination of the hypotheses identified 2 strong gradients.
- Along one gradient, the hypotheses were sorted by their popularity, measured by the average credibility score given by the respondents.
- The 2nd gradient separated all hypotheses postulating adaptation to swimming or diving into their own group.
The average credibility scores given for different subgroups of the hypotheses were not related to respondent's age or nr of publications authored,
but (paleo)anthropologists were more critical of all hypotheses, and much more critical of the water-related ones, than were respondents representing other fields of expertise.
Most respondents did not find the water-related hypotheses likely, but only a small minority found them unscientific.
The most popular hypotheses were based on inherent drivers: they assumed the evolution of a trait to have been triggered by the prior emergence of another human-specific behavioral or morphological trait,
but opinions differed as to which of the traits came first.

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Not all "human traits" are exclusively *human* traits,
e.g. "bipedality" was already early-hominoid (Miocene):
google "aquarboreal".

Marc Verhaegen wrote:

> Not all "human traits" are exclusively *human* traits,
> e.g. "bipedality" was already early-hominoid (Miocene):
> google "aquarboreal".

The LCA was bipedal and had a hand the looked more like ours than
a Chimps. And nobody denies this.

Well, they rationalize it away... inventing ridiculous even idiotic dates
of divergence in order to push the LCA so far back they can pretend
it may have no been bipedal.

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