Off-centre | Science

Of apes, men and covid: The non-existent trajectory of evolution

Illustration: Getty Images/ iStock

Illustration: Getty Images/ iStock  

No, humans have not been brought to their knees by a ‘primitive’ virus. We have never been ‘superior’, just more complex and more vulnerable

A few years ago, my brother posed me a question: “If humans evolved from apes, why do apes and monkeys still exist?” He is not an evolution denier, he was simply being curious. The question stemmed from the assumption that if something superior arrives, the redundant must surely leave the scene.

I remembered my brother’s question again when I realised how strongly it is related to the irksome Instagram and WhatsApp posts of the past few weeks that talk of how a “primitive” or “insignificant” coronavirus has brought the “mighty” human race to its knees.

In biological or evolutionary discourse, “primitive” is a word generally prefixed to organisms that evolved several millennia before the macro-organisms we are more familiar with. The word sticks in the minds of school students, and so most people lead lives with a sense of their superiority over all other organisms. This confidence may be misplaced.

Every living thing is essentially formed of atoms and molecules governed by the laws of physics. The atoms and electrons composing cellular structures come with physics rules applicable to all living beings at their most fundamental level. So, is the cell the most basic entity we know to be living?

Well, we have viruses, which do not resemble cellular structures at all. They are simply conscient molecules, for want of a better phrase. A few molecules of an acid (ribonucleic acid or RNA) encased within oil (lipid layer) is how any hetero-virus can be briefly introduced.

Even though evolution led to speciation, or the formation of new species, the “primitive” ones continued to exist mainly for one reason: they were successful in their niche.

The concept of the niche is better understood when we look at it from the ‘competitive exclusion principle’, which states that no two species can have the same niche, that is, compete for the same resources within the same space at the same time. On a long enough timeline, one species will out-compete the other and obliterate it.

Resource partitioning

For instance, when several fish species live in the same river, some fish will prefer faster flowing sections as they may have features such as a sucker-disc that allows them to hold on to rocks as water gushes around their streamlined bodies.

Other, larger fish may prefer deeper, slower sections, while some move to parts with overhanging vegetation so they can feed on falling leaf litter or insects. This is known as resource partitioning, which allows extremely similar organisms to coexist in the same habitat.

In ecology, a niche is generally attributed to an entire species. But we must remember that speciation is possible only because of differences among individuals within the population. The differences between individuals of the same species are also because of the differences at the genetic or molecular level. So, genetic differences are responsible not just for differences between species, but also for variations within them.

Molecules (of DNA) that form genes have constantly ‘tried’ to mix and match and push for a greater diversity of genetic information. It is wrong to consider any of these genes obsolete or primitive. Parasites are one of the best examples of organisms that consistently seem archaic in terms of somatic (body-related) complexity, but are the most up-to-date. The simpler the organism, the easier it is for the gene to transform and produce starkly different varieties within its population.

Subtle variations

So, when we look at complex genomes such as that of humans, where approximately 90% of the genetic material is junk, profound differences amongst individuals are rare. Instead, what we see are “subtle” variations in mental capabilities or eye colour. Of course, a lot of the variety between individuals owes also to environmental factors and life experiences, compounded by meta-thinking, at least for humans.

Finally, to answer my brother’s question: evolution is not directional. There are several species that came into being with associated functions (niches). In fact, if one were to plot all, or some, of the species on a graph for reproductive success and affluence, we would get a scatter graph that would show no relation to the evolutionary timescale. In other words, the organisms that rank higher in terms of reproductive success, genetic diversity, and abundance of required resources need not have necessarily evolved later than the ones that rank lower on the same parameters.

Viruses and bacteria have long been considered “primitive” creatures. Their genetic information was never complex, and this is one of the primary reasons they continue to successfully infect humans and other ‘highly evolved’ organisms. They can mutate easily, providing for various genetic combinations (recombinants), which can in turn be selected through natural processes. This enables them to be a step ahead of the defence systems of host organisms.

An analogy to understand this could be to compare two phone games, say sudoku and a car racing game. Yes, the car game is much more complex but Sudoku is not obsolete. In fact, Sudoku will need fewer ‘bug’ fixes and can work even without the internet.

So, in the context of COVID-19, statements such as “a primitive creature showing humans their place on the planet” don’t really mean much because we were never beyond the coronaviruses’ reach. We have never been ‘superior’. We are just more complex and thus possibly more susceptible.

The writer teaches at a Delhi University college.

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Printable version | Jun 1, 2020 2:43:30 PM | https://www.thehindu.com/sci-tech/science/of-apes-men-and-covid-the-non-existent-trajectory-of-evolution/article31590485.ece

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