Early Homo, plasticity and the extended evolutionary synthesis

Area of Science:

• Paleoanthropology
• Evolutionary Biology
• Human Evolution

Background:

• The Modern Synthesis advanced human evolution understanding, focusing on heritable traits and species classification from fossil records.
• Fragmentary fossil records often treat individual phenotypic variation as noise, overlooking its adaptive significance.
• The extended evolutionary synthesis emphasizes plasticity and non-genetic factors in generating novel phenotypes.

Purpose of the Study:

• To explore how plasticity and non-genetic influences on phenotypes can offer new interpretations of the human fossil record.
• To re-evaluate early *Homo* fossil interpretations by considering intraspecific phenotypic variation.
• To propose alternative hypotheses for early human evolution, species diversity, and diversification patterns.

Main Methods:

• Reviewing evidence from contemporary human populations on phenotypes responsive to non-genetic drivers.
• Analyzing how these non-genetic drivers inform interpretations of the fossil record, particularly for early *Homo*.
• Considering intraspecific phenotypic variation as a key factor in evolutionary processes.

Main Results:

• Phenotypic variation, driven by non-genetic factors like plasticity, offers valuable insights into population adaptation.
• Reinterpreting the fossil record through the lens of phenotypic variation provides alternative hypotheses for early human evolution.
• Contemporary human data can illuminate aspects of adult phenotypes relevant to fossil interpretation.

Conclusions:

• Paying closer attention to intraspecific phenotypic variation, beyond species means, is crucial for evolutionary insights.
• This approach can generate novel hypotheses regarding Early Pleistocene species diversity.
• Understanding phenotypic variation is foundational for explaining the dispersal and diversification of *Homo erectus* and its descendants.