Human evolution: living in rougher places (Introduction)

by David Turell , Thursday, October 10, 2024, 15:48 (8 days ago) @ David Turell
edited by David Turell, Thursday, October 10, 2024, 15:53

Theory is it helped us develop well:

https://www.science.org/doi/10.1126/sciadv.adq3613?utm_source=sfmc&utm_medium=email...

"Abstract
Over the past 3 million years, humans have expanded their ecological niche and adapted to more diverse environments. The temporal evolution and underlying drivers behind this niche expansion remain largely unknown. By combining archeological findings with landscape topographic data and model simulations of the climate and biomes, we show that human sites clustered in areas with increased terrain roughness, corresponding to higher levels of biodiversity. We find a gradual increase in human habitat preferences toward rough terrains until about 1.1 million years ago (Ma), followed by a 300 thousand-year-long contraction of the ecological niche. This period coincided with the Mid-Pleistocene Transition [MPT] and previously hypothesized ancestral population bottlenecks. Our statistical analysis further reveals that from 0.8 Ma onward, the human niche expanded again, with human species (e.g., H. heidelbergensis, H. neanderthalensis, and H. sapiens) adapting to rougher terrain, colder and drier conditions, and toward regions of higher ecological diversity.

"DISCUSSION
The results shown here expand our understanding of the environmental factors that shaped hominin behavioral strategies and their evolutionary trajectories. Our analysis does not rely on the construction of an explicit environmental niche model; we simply analyze the climate and vegetation conditions and estimates of terrain roughness at previously reported sites of hominin presence. Our aggregated statistical analysis reveals that human species adapted to landscapes that were characterized by regionally increased biome diversity, as stipulated in the previously proposed Diversity Selection Hypothesis, and that this ecotone inclination was realized in particular in regions with higher terrain roughness. According to our analysis, area roughness is the most important predictor of human biome diversity at sites of hominin occupation, exceeding even the contributions of the key climatic variables temperature and precipitation. This result supports the notion that terrain roughness (slope) is an important predictor in hominin studies and niche modeling.

"Human adaptation toward increasing area roughness occurred in two major phases: The first one, from 2 to 1.1 Ma, was interrupted by a substantial decrease during the MPT. The second adaptation phase, 0.9 to 0.1 Ma, coincided with the expansion of H. heidelbergensis and H. neanderthalensis into Europe and the general positive trend in the brain size of hominins. The niche contraction during the MPT, which occurred mostly in Africa, coincided with several major evolutionary events. In Africa, recent studies suggest a human population bottleneck, which reportedly reduced the genomic diversity of humans by a factor of ~80. The timing also roughly matches with estimates of when the fusion of human chromosome 2 (found in Denisovans, Neanderthals, and H. sapiens) took place, although the dating uncertainties for this genomic transition still remain large. MPT climate variability might have also been a factor in the extinction of other genera and species, such as Paranthropus robustus. These different lines of evidence suggest that climatic and ecosystem changes during the MPT transition may have played a major role in hominin evolution.

"Even when categorizing hominins into groups based on their terrain roughness tolerance (low, medium, and high), we find that terrain roughness continues to be the dominant contributor to increased biome diversity across all groups relative to temperature and precipitation contributions. The areas with medium and high roughness are particularly abundant with diverse food resources, environmental niches, and potential natural shelters to mitigate weather and climate extremes. These characteristics may have contributed to the survival and overall evolution of the genus Homo, increasing their resilience and versatility.

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"...our analysis agrees with other lines of independent evidence (18–20) that point to the importance of terrain roughness as a key factor in human habitat suitability regionally and on continental scales. Investigating the relationship between environmental heterogeneity, resource availability, and energy expenditure presents a promising avenue for future research."

Comment: our extraordinary abilities allowed this type of activity in diversity, and helped refine them as top predator as in this observation:

https://mail.google.com/mail/u/0/#inbox/FMfcgzQXJZtWljJpzVhNgPsHDwKjTXNx

"The authors suggest our ancestors sought uncomfortable habitats because “areas with medium and high roughness are particularly abundant with diverse food resources, environmental niches, and potential natural shelters to mitigate weather and climate extremes.” That may have meant traveling less for necessities, allowing ancient humans to devote “more time and resources to other activities, such as social interactions or tool production.” So ultimately, taking the road less traveled “may have contributed to the survival and overall evolution of the genus Homo.”