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Hypothesis

Ticks, Hair Loss, and Non-Clinging Babies: A Novel Tick-Based Hypothesis for the Evolutionary Divergence of Humans and Chimpanzees

Independent Researcher, Saddle Brook, NJ 07663, USA
Academic Editors: Koichiro Tamura and Kousuke Hanada
Life 2021, 11(5), 435; https://doi.org/10.3390/life11050435
Received: 10 March 2021 / Revised: 12 April 2021 / Accepted: 30 April 2021 / Published: 12 May 2021
(This article belongs to the Section Evolutionary Biology)
Human straight-legged bipedalism represents one of the earliest events in the evolutionary split between humans (Homo spp.) and chimpanzees (Pan spp.), although its selective basis is a mystery. A carrying-related hypothesis has recently been proposed in which hair loss within the hominin lineage resulted in the inability of babies to cling to their mothers, requiring mothers to walk upright to carry their babies. However, a question remains for this model: what drove the hair loss that resulted in upright walking? Observers since Darwin have suggested that hair loss in humans may represent an evolutionary strategy for defence against ticks. The aim of this review is to propose and evaluate a novel tick-based evolutionary hypothesis wherein forest fragmentation in hominin paleoenvironments created conditions that were favourable for tick proliferation, selecting for hair loss in hominins and grooming behaviour in chimpanzees as divergent anti-tick strategies. It is argued that these divergent anti-tick strategies resulted in different methods for carrying babies, driving the locomotor divergence of humans and chimpanzees. View Full-Text
Keywords: forest fragmentation; parasites; last common ancestor; bipedalism; knuckle-walking; social grooming forest fragmentation; parasites; last common ancestor; bipedalism; knuckle-walking; social grooming
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MDPI and ACS Style

Brown, J.G. Ticks, Hair Loss, and Non-Clinging Babies: A Novel Tick-Based Hypothesis for the Evolutionary Divergence of Humans and Chimpanzees. Life 2021, 11, 435. https://doi.org/10.3390/life11050435

AMA Style

Brown JG. Ticks, Hair Loss, and Non-Clinging Babies: A Novel Tick-Based Hypothesis for the Evolutionary Divergence of Humans and Chimpanzees. Life. 2021; 11(5):435. https://doi.org/10.3390/life11050435

Chicago/Turabian Style

Brown, Jeffrey G. 2021. "Ticks, Hair Loss, and Non-Clinging Babies: A Novel Tick-Based Hypothesis for the Evolutionary Divergence of Humans and Chimpanzees" Life 11, no. 5: 435. https://doi.org/10.3390/life11050435

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