A brewing debate on evolution theory picks up in India

Debaters (From left) N.G. Prasad, Sutirth Dey, Amitabh Joshi and T.N.C. Vidya get together periodically to work on conceptual issues at the foundations of genetics and evolutionary biology.   | Photo Credit: Special arrangement

The phenomenon of niche construction in evolutionary biology has been mooted to be highly important but neglected in evolutionary biology theory. Not just that, it has been termed a concept at par with natural selection. Five Indian evolutionary biologists connected to Evolutionary & Organismal Biology Unit of JNCASR, Bengaluru, have set out to show that this is not so. Apart from citing instances of the concept’s use in earlier papers, they also argue that incorporating the phenomenon does not involve a major reworking of Standard Evolutionary Theory (SET). Their paper is soon to be published in the Journal of Genetics.

Over the last two decades, niche construction – the phenomenon by which evolving organisms modify their environment, which in turn increases or decreases their own survival rate – has become much talked about in the literature. Proponents of this theory have argued that it has been neglected in the Standard Evolutionary Theory, which therefore needs a major overhauling. This has been debunked in the paper by the authors. When posted on the Biorxiv, the paper got an unprecedented level of attention.

A new domain

It is interesting that evolutionary biologists from India are engaging in this debate on the concepts of evolutionary theory. Amitabh Joshi, one of the five authors of the paper, remarks, “We biologists from India have largely added to the compendium of facts, sometimes (mostly Indian ecologists and evolutionary biologists) to theoretical concepts, but hardly ever to fundamental debates about the conceptual foundations of the subject. For example, the foundational debates within evolutionary biology for the past 15 years have been dominated by scientists from North America and Western Europe.”

One of the contentions of the authors is that contrary to the claims that Niche Construction has been neglected in the Standard Evolutionary Theory, they show in the paper that it has been considered by many authors to explain phenomena, even before the term “niche construction” was coined. One of the examples they give is of an experimental study done by Borash and others in 1998: The experiment involved breeding larvae of fruit fly, Drosophila melanogaster, in an environment where food was reduced and presence of nitrogenous waste was increased. It was observed that even within one generation the larvae that formed early became heavy feeders and the late developers grew to become waste tolerant. Thus, within one generation, they were able to observe the effect of environment that was altered by the organism (the heavy feeders depleting the environment of food for the late developers). They found that it introduced the above polymorphism – separation into heavy feeders and waste tolerant types.

Proponents of niche construction use the following examples often: The use of lactose to feed adult humans – which is believed to have evolved along with cattle husbandry – and the high incidence of sickle cell anaemia in populations where there is a prevalence of malaria, due to yam cultivation. The authors debunk the claims by citing references of the above examples already having been used within the classical theory itself.

Other claims

They also deny some of the oft-quoted claims about it: for instance, that NC is more than an alternative perspective, and it is a serious body of formal evolutionary theory or that NC is an evolutionary process, at par with natural selection.

The article has drawn the attention of the international community as well. Prof. Jerry Coyne, eminent biologist and recipient of the Richard Dawkins award has written a blog post in which he agrees with most of the points made in the paper.

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Printable version | Oct 28, 2020 7:26:45 PM |

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