Evolutionary Misunderstanding

For my last proper column of the year, I wanted to look at something that occurs regularly in the media that bothers me personally because of my day job as a medical reporter, but also generally speaking, as it undermines public understanding of science.

It seems that many, many journalists, and also some academics, do not understand how evolution works and put the cart before the horse, so to speak. I have seen in print and online, and heard on the radio, hundreds of examples, and every time I come across one, it gives me an unpleasant jolt.

Because of the mistake occurring so often, it is a little unfair to pick out one article, but my attention was recently drawn to a fascinating example in a book review in the New York Times, of all places.

Cindi Leive discussed Eve by Cat Bohannon, which Leive describes as “an opinionated clapback against centuries of male-centric evolutionary history” that “wants us to wrest our attention away from ‘the clever ape — always male’ and turn to an alternative set of protagonists: the Eves.”

I immediately loved the idea of this book and wanted to read it straightaway, even without going any further into the review, especially when Leive says: “Bohannon has different protagonists in mind, and she whips through the millennia sketching early ‘Eves’ who may have gotten us where we are now, from a lactating ‘weird little weasel-beast’ of dinosaur times to Ardipithecus ramidus, the first known ape to walk upright."

That sounds exactly my cup of tea. However, Leive went straight onto extremely shaky ground when discussing the book in greater detail.

It started innocently enough, with this: ”And if you’re talking about pivotal evolutionary breakthroughs, consider nursing. Not only does the infant’s mouth prompt the mother’s body to make milk, but research shows that the milk is a magically on-demand concoction, ‘co-produced’ in response to signals that the baby sends by flowing its saliva into the mother’s nipple to indicate it is stressed or sick and in need of a specific recipe.”

So far so good, and I was keen to read what would come next. Sadly, it was this:

“Our bodies did all this because it was necessary, Bohannon argues. The thing our species has always needed most is the survival of its babies — and the creatures who bear and breastfeed them. ‘In the mammalian game, you can always make more boys,’ she notes. ‘The loss of a healthy, young female is incredibly expensive.’ (In this view of evolution, in other words: She’s Eve. He’s just Ken.)’

Sorry, Leive, and Bohannon, but that understanding of the evolutionary process is just wrong, wrong, wrong. To make it clear, here is the key mistake: “Our bodies did all this because it was necessary.”

I don’t blame Leive or even Bohannon, if they are not scientifically qualified, although it would have been nice if either one of them had done their research before putting pen to paper. Especially for Bohannon, before she started writing an entire book on the development of humankind from the female perspective, in which evolutionary considerations would inevitably play a large part. (And wouldn’t it have been nice if a suitably qualified editor had been assigned to her at Knopf, her publisher).

The reason why I don’t blame them is because this very same mistake is made over and over and over again in popular science and medical writing, and I have even seen it in academic articles published in venerable journals that, frankly, should know better.

So, yes, it is a little unfair to pick on one article, when there is so many to choose from, but this one was so egregious that it made my point perfectly.

(In the interests of balance, I also found an example in the 11 November issue of The Week. In a piece on the discovery that chimpanzees appear to undergo the menopause, there was this flagrant misunderstanding: “Menopause is thought to have evolved in humans so that so that there are older women available to help rear grandchildren, but the ‘grandmother hypothesis’ cannot explain menopause in chimps, as the females don’t live in the same groups as their mothers.” Again, utterly wrong and back to front.)

But what is the mistake they are making? How are they so wide of the mark in their understanding of how humans, or indeed any other organism, arrived at their current form and with with their ingrained societal behaviours?

Before we go on, I want to reassure you that this is not going to be an in-depth scientific analysis. I shall merely skim across the surface of evolution as a topic, delving only as deep as is necessary to understand why the articles are so wrong.

Let’s begin by assuming that people understand the majority of human cells contain strands of DNA, twisted into a double helix. Also, that sections of those strands form what we call genes, and that these genes, when ‘expressed’, are code for proteins that have a function in our bodies, such as hormones, or antibodies, or enzymes that break down food in our stomachs, or the fibres that form our muscles.

It’s not quite so simple as all that of course, as there are other genes that turn ‘on’ or ‘off’ those that make important proteins, and there are even what one might call accelerator and decelerator genes.

On top of that, there is a lot of ‘nonsense’ code in the DNA, which is thought to help in the constant battle against mistakes when making copies of the DNA during cell division and replication.

There is even a concept called epigenetics, in which outside influences can have an impact on whether and how much a gene is read and encoded into a protein. Often people are thinking of environmental factors here, and an interesting one is famine.

Starvation appears to have a profound effect on the body, not just in terms of its immediate impact on nutrition but also by causing some genes to switch on and others to switch off. Crucially, this modification of gene expression can be passed on to someone’s offspring.

A good example is the famine in Italy after the Second World War, which has been relatively well studied. It is worth noting, however, that Italy has suffered numerous famines throughout its history, and it would be fascinating to attempt to trace the influence of those on gene expression over the centuries.

But I digress.

Evolution is intertwined with the concept of alterations in genes over time, specifically genetic changes that have an impact on an organism, in this case human beings. These changes, via changes in the proteins they encode, can lead to variations in traits that affect the ability of the animal to reproduce and survive (although the key detail here is not survival per se but rather survival to reproductive age, which is the only aspect that makes a difference to evolution).

If the local environment remains stable and so the genetic changes continue to influence reproduction and survival, they and their accompanying traits may become common within a population, and so drive what we see as evolution.

But the key thing here is the genetic changes occur spontaneously, and the ones that have the biggest impact on evolution, because they are passed on to the offspring, are found in sperm or eggs. They can be due to mistakes made when the DNA was copied to make each sperm or egg, or induced by outside influences, such as chemical or radiation exposure, or disease, for example.

Now, genetic changes, broadly speaking, fall into one of three categories:

Disadvantageous: These are genetic changes that may be so severe that they cause death in the womb or in infancy, or have a major impact in early life. These typically are weeded out within a generation, as the person concerned usually does not reproduce. (There are exceptions to this, an interesting example being Huntington's disease, which can be passed on because it often strikes after standard reproductive age.)

Neutral: These are changes that have a minor effect on an organism, but don’t alter its ability to survive or reproduce. An example might be eye or hair colour, or the pattern of veins (as opposed to arteries) in the body, which is as unique to a person as their fingerprint. Or perhaps the ability to appreciate the taste of coriander.

Advantageous: A good example of beneficial genetic changes might be the sudden ability to see in colour, or to oppose one’s thumbs and so make precise tools or develop writing, or to be able to taste rancid foods and therefore be warned when something has gone off. These changes offer an immediate benefit, whether in terms of survival or reproduction.

But what does all this have to do with the articles above? The simple fact is that the genetic change, whether disadvantageous, neutral or advantageous comes first, followed by the effect of on the individual and its potential for an evolutionary change.

The genetic change is an ‘accident’ that we have to deal with, or use for our betterment and to take advantage of a situation. In other words, the changes in the gene or genes that resulted in new proteins that gave us opposable thumbs came first. Then we discovered that we could oppose our thumbs, which we then found was helpful in making tools or, later on, writings.

The mistake the articles make is in imagining that the changes occurred the way around: that someone was sitting around thinking it would be handy to be able to write a letter, or that it would be useful if women stopped reproducing at some point so they could help look after their grandchildren. Then somehow the body ‘felt’ that need, and altered its genes to produce the necessary proteins in their children to allowed them to perform that task.

It is as about as wrong headed as you can get.

While epigenetic changes may occur as a result of environmental pressures, the truth is that genetic changes occur all the time, and the environment drives us to keep or reject them, depending on how useful or otherwise they are.

To give you an example, this process will have to be relied upon, for example, if bees in the UK are to survive the hunting tactics of the invader Asian hornet, or wild birds are going to survive the spread of Avian flu. In the first case they might develop novel behaviours or changes in body colour or taste that put the Asian hornets off, while a sudden genetic change in a bird might give it resistance to Avian flu over and above that achievable by their current immune systems.

Sadly, we humans are unlikely to evolve any further. We have the sometimes questionable ability to mould our environment to our needs, rather than the other way around. We can identify a need and will an object into existence that can satisfy that need.

Although whether we really ‘need’ home foot spas or electrically powered racing cars is the subject of another debate.