How long does evolution take?

How quickly does evolution happen? The short answer is: it depends on what you are, and where you are.

Evolution is the process in which a living organisms’ heritable traits change as successive generations replace one another. And so if the physical changes of evolution are mostly instigated by molecular changes, therefore evolution only happens when it needs to. Animals like sharks and crocodiles have remained relatively unchanged for hundreds of millions of years because.. Well they just work. But they’re outliers in evolutionary terms, nearly everything else has undergone change in that time period. So how does the genetic mutation responsible for evolution happen? And here to explain is the University of Plymouth’s Andy Foggo.

The process starts with the occurrence of usually small, but heritable, changes in the genetic code of organisms These occur as a result of things like hybridization, mistakes in copying of the code when cells divide, and environmental triggers such as background radiation, from natural sources like sunlight.
These genetic changes which are the actual stuff of evolution can happen on a timescale of seconds, so in that sense evolution can be thought of as being very fast.
Getting these molecular changes to spread in a population to the point where the physical, chemical and behavioural differences between individuals result in new species, that takes much longer. This can range from a few weeks in the laboratory to millions of years in nature, there are no rules here.

Evolution is therefore both very, very fast, and unbelievably slow.  And since evolution can only happen when traits are passed down through generations, the speed at which an adaptation becomes the norm is specific to how large that organism is, how complex its genetic code is, and how quickly that organism can reproduce.

The things that affect the rate of evolution more than anything are the size of the organisms, and the environmental conditions in which they occur. Generally, the smaller the organism, the faster the generational turnover. The faster that turnover, the greater the chances of a change occurring, the greater the opportunities for natural selection to act and the faster the accumulation of difference.
But aside from that, there are other determining factors as well.

Environments with higher background levels of ionising radiation and higher temperatures usually have higher rates of cellular metabolism, division, mutation and hence opportunities for both forms of evolution too.
So unfortunately because of all of this, we can’t say what the speed of evolution is, but we can say that places like the tropical rainforest are where it happens the fastest.