Several very interesting recent papers in Science, but they often forget comparative & some other evidence, e.g.
- the absence of African Pliocene retroviral DNA in humans confirms our Pliocene ancestors followed the S-Asian coasts (Mojokerto, Java etc.):
- at least 8 independent indications show archaic Homo frequently dived (see below),
- compar.anatomy: African australopiths more closely resembled Gorilla (e.g.. E.Afr.afarensis->boisei) or else Pan (e.g. S.Afr.africanus->robustus)
https://www.gondwanatalks.com/l/the-waterside-hypothesis-wading-led-to-upright-walking-in-early-humans/

Human Evolution Reconstructing the past
Sacha Vignieri 2023 Science 381
Most of what we know about hominin evolution comes from fossil evidence,(?? compar.biology !! --mv)
and these fossils come from a world shaped by climate & ecol.dynamics, as ours is today.
The ability to estimate these past environments permits us to better understand the forces that shaped our evolution.
2 studies now use climate models to estimate past environments & spatial distribution models to predict species occurrence,
they reveal details about hominin evolution that fossils alone cannot (see Perspective by Beverly):
-- Ruan cs looked at Hn & Hd habitat overlap,(neand.-denisova) they found patterns of interbreeding that correlate with climate & environmental change in Eurasia.
-- Margari cs have identified a previously unknown climate-driven depopulation of hominins in S-Europe early-Pleistocene.
Science, add4459, adf4445, this issue p.699, 693 see also adj4631 p.605

Using climate to model ancient human migration - Modeling fills gaps in the fossil record of early hominin movement from Africa
Emily J Beverly 2023 Science 381:605-6 doi 10.1126/science.adj4631
Over the past 30 yrs, studying hominin evolution has shifted, from locating fossils & artifacts, to understanding the ecol.drivers behind where these items are found.
Since these materials were first discovered, many drivers of hominin evolution have been hypothesized,
but testing these ideas is difficult because of
- limited data on environmental & climate factors that could have influenced migration &
- the challenges of establishing the age of the sediments in which the materials are found.
Margari cs p.693 & Ruan cs p.699 address these difficulties, by modeling how climate & eco-systems changed during various periods over the past 3 Ma..
A similar approach was also described by Zeller cs (Science 380:604, 2023).
These models use current understanding of the environment & climate, to extrapolate from incomplete records, and provide ecol.context for evol.changes..

Climate shifts orchestrated hominin interbreeding events across Eurasia
Jiaoyang Ruan cs 2023 Science 381:699-704 doi 10.1126/science.add4459
When, where & how often hominin interbreeding happened is largely unknown.
We study the potential for Hn-Hd admixture:
we use spp distribution models that integrate extensive fossil, archaeol. & genetic data + transient coupled general circulation model simulations of global climate & biomes.
Our Pleistocene hindcast of past hominins’ habitat suitability reveals pronounced climate-driven zonal shifts in the main overlap region of Hd & Hn in C-Eurasia.
These shifts (which influenced the timing & intensity of potential interbreeding events) can be attributed to the response of climate & vegetation to past variations in atm.CO2 & N-Hemisphere ice-sheet volume:
glacial-interglacial climate swings likely played an important role in favoring gene-flow between archaic humans.

Extreme glacial cooling likely led to hominin depopulation of Europe in the Early Pleistocene
Vasiliki Margari cs 2023 Science 381:693-9 doi 10.1126/science.adf4445
The oldest known hominin remains in Europe (c 1.5 - 1.1 Ma) have been recovered from Iberia, where paleo-environm.reconstructions have indicated warm+wet inter-glacials & mild glacials, supporting the view: once established, hominin populations persisted continuously.
We report analyses of marine & terrestrial proxies from a deep-sea core on the Portugese margin,
these show pronounced millennial-scale climate variability during a glacial period c 1.154 - 1.123 Ma, culminating in a terminal stadial cooling cf the most extreme events of the last 400 ka.
Climate envelope–model simulations reveal a drastic decrease in early hominin habitat suitability around the Med during the terminal stadial.
We suggest: these extreme conditions led to the depopulation of Europe, perhaps lasting for several successive glacial-interglacial cycles.

Human adaptation to diverse biomes over the past 3 million years
Elke Zeller cs 2023 Science 380:604-8
We investigate the role of vegetation & eco-system diversity on hominin adaptation & migration,
we identify past human habitat preferences over time, using a transient 3-Ma earth system-biome model simulation + an extensive hominin fossil & archaeological data-base.
Our analysis shows: early African hominins predom.lived in open environments such as grassland & dry shrubland. (?? --mv)
Migrating into Eurasia, hominins adapted to a broader range of biomes over time.
By linking the location & age of hominin sites with corresponding simulated regional biomes, we also find:
our ancestors actively selected for spatially diverse environments.
The quantitative results lead to a new diversity hypothesis: Homo spp (in particular Hs) were specially equipped to adapt to landscape mosaics.

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Pleistocene archaic Homo was littoral:
• Brain size in erectus (2x apes-australopiths) is facilitated by sea-foods, e.g. DHA docosahexaenoic acid in shellfish… e.g. Odontocetes, Pinnipedia...
• Homo’s intercontinental dispersals = coastal.
• Pleist.Homo colonized islands far oversea (Flores, later even Luzon) https://www.academia.edu/36193382/Coastal_Dispersal_of_Pleistocene_Homo_2018
• H.erectus s.s. fossilized typically in coastal sediments: Mojokerto: barnacles, corals; Trinil: Pseudodon, Elongaria; Sangiran-17 "brackish marsh near the coast"…
• Stephen Munro's sea-shell engravings made by H.erectus, Joordens cs 2015 Nature 518:228–231 https://pubmed.ncbi.nlm.nih.gov/25470048/
• Archaic Homo's atypical tooth-wear is caused by "sand & oral processing of marine mollusks", Towle cs 2022 https://onlinelibrary.wiley.com/doi/10.1002/ajpa.24500
• Ear exostoses (H.erectus & H.neand.) develop after years of cold(er) water irrigation https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5696936/
• Pachyosteosclerosis is only seen in slow+shallow-diving tetrapods, de Buffrénil cs 2010 J.Mamm.Evol.17:101, e.g. erectus’ parietal bone is 2x as thick as in gorillas.
• Homo’s stone tool use & dexterity is typical for molluscivores, cf. sea-otters…