Skip to main content

Variety is the spice of life


Natural selection acts on variation between organisms. In fact, evolution itself would be impossible without variation. If you have a population where most or all individuals are not varied, then there is no way the population is going to be able to adapt over time, so potential for change doesn’t exist. Adaptation can’t arise spontaneously just because it is needed.

For example, the case of the black and white moths during a time when tree trunks were painted white is a good illustration of this principle. You start with an even variation of about 50-50 between black moths and white moths. The tree trunks get painted white, so clearly the black moths will contrast highly with the white trunks. They are visible to predators, and so most die out, don’t get a chance to reproduce, therefore don’t pass on the gene (allele) that codes for their black colour. As a result, future generations have few black individuals, and a lot more white ones (as the white moths were well camouflaged so were not that visible to predators).


The point is, what would have happened to that moth population had there been no white moths at all? It’s not far-fetched to speculate that that specific population might well have died out. But imagine this: think about our current, mostly white moth population. What if the tree trunk dye gets washed away, and the white moths now appear obvious on the trunks? Does that mean the population is bound to die off anyway at some point in the future? It becomes obvious that, despite directional natural selection (directional means favouring one extreme attribute rather than another), some variation must be maintained. Indeed, some variation is always maintained by many very different processes, from the molecular level to the ecosystems. Find out about these in the next post.

Comments

Popular posts from this blog

4 Reasons Google's Calico Won't "Solve Death"

The on-line world has been taken ablaze by Calico's bid to end ageing, and thus death itself, but is this what they will actually focus on, and will they achieve it? The fact is ageing will be reversed, and death by "natural causes" will go with it. The questions are "When?" and "By whom?". Until recently, not a lot was known about the approach Calico would take in this venture dubbed "moonshot thinking" - a term touted by Google as the source of all considerable human progress throughout history. This we don't doubt, but is this what Calico is all about? CNN's Dan Primack has revealed details about Calico's plan , which hint at a less-than-moonshot thinking approach, and cast a serious question mark on its ability to deliver the punchy TIME headline. Here is why: 1. The man with the idea, Bill Maris, arrived at the conclusion that the root of all death-causing disease is simply ageing itself. Not only is this widely

The evolution of the human body

In order to be able to look at ourselves in the mirror and be able to answer the question "Why do I look like this?", we must look back to our ancestry and their lifestyle, over a very long period of time. For the purpose of this analysis, let's look at the human versus the neanderthal. Recently there have been found neanderthal genes within the human gene pool, but the two species are different enough to compare, yet not too different (human versus fly would be too different). As you can see, the construction of the human pelvis and toes is different, and the human has less hair. This results in humans being able to run easily for long distances, in the detriment of short-distance running which we are worse at. We sweat better, so we can do more long-term effort. This feat is essential to better settlements, as we can discover a larger area with potentially better resources. It might seem counterproductive to not be able to run quickly for a short period, when it come

First Blog, Ever.

Before we start to explore evolution, let me outline what this blog is about, and what approaches it will take. Most people are aware of the theory of evolution. However, the predominant context of it has been restricted to the animal kingdom, and the most obvious animal of all has been ommitted: you, the human. Us, Homo sapiens. Articles of so-called "evolutionary psychology" may jump up in your head right now. Something about the colours women wear, or the jobs men want. Something about sex, something about money. Something silly. This blog aims to explore the fundamental principles of life and evolution, and apply them to the surrounding world, with an emphasis on humans. This blog aims to challenge evolutionary psychology with evolutionary biology. This blog aims to cast light on many dark areas such as: What is the cause, course and effect of life? Are there principles which apply to all forms of life, on Earth and other places in the Universe? Can we predict life fo