Antisocial bees point to autism’s ancient genetic origins
Genetic similarities between unresponsive bees and humans with autism give air to the controversial ideas of sociobiology
The controversial evolutionary theory known as sociobiology is set to return to the critical spotlight following the publication of research that suggests genetic similarities drive behaviour patterns in bees and people with autism.
The study, led by Hagai Shpigler of the University of Illinois at Urbana–Champaign and published in the Proceedings of the National Academy of Sciences, reports similar gene expression signatures in bees that don’t respond to social stimuli and in people with autism. This, the scientists suggest, indicates genes associated with autism-like behaviour are deeply conserved – that is, they are ancient in origin and found in species with which humans have not shared a common ancestor for hundreds of millions of years.
To make their findings, Shpigler and colleagues exposed a wide variety of individual bees to two stimuli: a bee from a different colony, which usually elicits an aggressive response; and a queen larva, which usually prompts a nurturing response.
A significant subset of the target bees did not respond to neither stimuli. Taking these particular insects, the team recorded the gene expression signatures found in structures known as mushroom bodies, within the high-level integration centre of the brain.
The signatures revealed particular genes expressed very differently between the responsive and unresponsive bees. Comparing the signatures to those found in humans with autism, the researchers found significant overlap, suggesting the genes governing social behaviours are ancient and strongly conserved.
This, write Shpigler and his colleagues, fits the sociobiological model, which holds “that similarities between human and animal societies reflect similar evolutionary origins”.
This suggestion is likely to be widely debated because it explicitly presents the research findings as evidence in support of the theory of sociobiology, first introduced by biologist E.O. Wilson in 1975.
Wilson, drawing on examples found in eusocial insects such as ants, suggested social behaviours including altruism and aggression were driven by genetic rather than cultural factors.
This in turn suggested that evolutionary success – the passing on of genes – operated on the level of kin, or family, rather than the individual. Organisms that did not reproduce but instead devoted time to looking after a relative’s offspring – or organisms that choose to die to protect nieces and nephews – did so to maximise the chances of kin genes being passed on. Self-sacrifice, thus, is about genes, not goodness.
Wilson’s theory was immediately and lastingly controversial, generating a bitter division among evolutionary biologists that continues today. The most recent outbreak of hostilities occurred in 2012, when Wilson published a new book, The Social Conquest of Earth, refining and extending his theories.
The book was met with a furious response from Richard Dawkins, who wrote that reading it entailed wading “through many pages of erroneous and downright perverse misunderstandings of evolutionary theory”.
The debate continues, with sociobiology fans and critics engaged in long – and extremely healthy – arguments about how exactly gene expression is controlled, and how it influences behavior.
Shpigler and his colleagues acknowledge their findings do not definitely establish that non-responsive behaviours seen in some bees and people with autism stem from genes passed on by some distant common ancestor. The evidence might equally – and rather unsociobiologically – indicate only a coincidence.
“Despite profound differences between honey bee and human societies, we have documented strong similarities in the genes associated with social responsiveness,” they conclude. “It is not possible to discern whether these similarities arose from either common ancestry or convergent evolution.”