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Outline
1. A brief history of hominin fossils 2. Putting evolution in context: the potential role of landscapes 3. From trees to bushes: diversity, mosaic evolution and reticulation 4. From ‘heroic’ models to complex ones –
understanding our relatives’ roles in their own histories
Reticulated (network) evolution, landscape and agency – what the new fossils tell us
Isabelle Winder
A fossil timeline
A fossil timeline
Neanderthal 1, Germany Engis, Belgium (1830)
Cro‐Magnon, France
Homo neanderthalensis named by William King
Neanderthals, including from Spy, Belgium
Forbes Quarry, Gibraltar (1848)
1856
2015
1856
A fossil timeline
Java, Indonesia
1856
2015
A fossil timeline
Mauer, Heidelberg, Germany
Taung, South Africa
2015
1856
Piltdown, England
2015
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A fossil timeline
Evolutionary contexts
Piltdown disproven (1953)
Homo transvaalensis
Homo erectus
Australopiths
1856
Homo sapiens
Early Homo
Earliest hominins
2015
Later Homo
The savannah hypothesis
Lewin (2005) An Illustrated Guide to Human Evolution; Gibbons (2009) Nature; DeMenocal
(2004) Earth and Planetary Science Letters.
Forest hypotheses
“For the production of man a different apprenticeship was needed…. In my opinion, Southern Africa, by providing a vast open country with occasional wooded belts and a relative scarcity of water, together with fierce and bitter mammalian competition, furnished a laboratory such as was essential to this penultimate phase of human evolution”
Raymond Dart
Dart (1925, p.199) Nature
The aquatic ape
Variability hypotheses
DeMenocal (2004) Earth and Planetary Science Letters; Potts (1998) Evolutionary Anthropology;
Vrba (1992) Journal of Mammalogy
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A brief summary
A key challenge...
What’s missing?
Complex landscapes
Winder et al. (2013) Antiquity
King and Bailey (2006) Antiquity;
Bailey and King (2011) JHE
Winder et al. (in press) Antiquity.
Moving into complex landscapes
Humans and complex landscapes
Brown and Yalden (1973) Mammal Review
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Putting it all together: ‘scrambler man’?
Putting it all together: ‘scrambler man’?
Winder et al. 2013) Antiquity
Hominin diversity
Diversity within groups: Dmanisi
Fossil diversity has increased in two ways:
1. With the recognition and description of new species (often based on small samples)...
2. ...and with the discovery of increasing diversity within species, including both morphological, ecological and genetic variation
Overlaps between groups: genus Homo
Genetic evidence
• A further 4‐6% of the • 1‐4% of the non‐African Melanesian genome may human genome may derive derive from the ‘Denisova’ from Neanderthals
hominins
• There are several possible explanations…
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Fossil evidence: hybrids?
Fossil evidence: mosaics
Duarte et al. (2011) PNAS; Soficaru et al. (2006) PNAS.
Is this evidence for a new model of evolution?
HETERARCHICAL OR “RETICULATE” EVOLUTION
HIERARCHICAL EVOLUTION
Fossil evidence: mosaics
Reticulation among other primates: the Papionins
Reticulation among other primates: Papio
Lang (2006a, b) Primate Factsheets
Gilbert (2011) AJPA
Zinner et al. (2009) BMC Evolutionary Biology
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Reticulation among other primates: Rungwecebus
Jones et al. (2005) Science; Burrell et al. (2009) Molecular Phylogenetics and Evolution
Reticulation among other primates: apes
Wolkin and Myers (1980) Science
Agency and non‐adaptive evolution
What precisely is an adaptation?
An adaptation is:
• Heritable
• Functional (i.e. actually capable of performing a function)
• Adaptive (i.e. contributing to fitness for those individuals that have it)
• Currently used for the function for which it was originally selected
An example: feathers as an adaptation for flight
Alternatives to adaptation
Are key human traits adaptive?
Adaptation
Exaptation
Something else
A structure shaped by natural selection for its current use
A structure that performs a function but which was not shaped for that purpose
Spandrels, survivable non‐adaptations, neutral/random traits...
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What if we aren’t adapted?
The vulnerable (compassionate!) ape
• Humans also produce a relatively large number of disabled (or differently abled) individuals
• Some high‐functioning ‘disabilities’ may have benefits to the group, but many cannot be explained this way
• Must we really argue that our ancestors, as hairless, weak‐jawed, straight‐footed apes with congenitally encephalised offspring were somehow fitter than other apes?
Conclusions
• The rapid growth of the fossil record gives us ever more insight into human evolution, and, together with theoretical developments, is helping generate brand new theories
• Just three examples come from our new understanding of hominins’ preferences for complex, heterogeneous landscapes, the role(s) of mosaics and reticulation, and the potential significance of agency and compassion...
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