Nic Shakeshaft, Kings College London
Are you one of those people who never forgets a fact but canít remember a face? If so, you can probably blame your genes, according to new research published in Proceedings of the National Academy of Sciences this week. Theyíve been investigating the genetics of face recognition with the help of a thousand pairs of twins, as Nic Shakeshaft explains to Kat Arney...
Nic - People differ a lot in how good they are at recognising faces. Obviously, being able to do is quite an important social skill and there's some suggestion that it might have been very important from an evolutionary point of view Ė telling friend from foe easily. So, we were very interested to look at it from that point of view and being able to do this with a twin study allows us to look at the genetic influences and relate it to abilities in other areas.
Kat - So, how do you use twins to figure out how genetic something is?
Nic - Obviously, two types of twins - identical and fraternal twins. Identical twins share all of their genes whereas fraternal twins on average only half, but both type share their environments to approximately the same extent. If we compare the degree of similarity, the correlation between identical twins and between fraternal twins, then we can use that in various statistical ways to look at the degree of genetic influence.
Kat - So, if identical twins are better at doing a certain task than non-identical twins, you'd say there's probably more of a genetic component to that ability.
Nic - Exactly, yes. Also, if we look at it by comparing genetic influences on different traits then we can also work out the extent to which they shared genes in common.
Kat - How were you actually doing this study?
Nic - We did it online. We have a large group of twins who have been studied throughout their lives and we used a standard test of face recognition, which just gets people to memorise a set of previously unfamiliar faces and then tests their ability to recognise them.
Kat - What do you find when you look at the data? Does this ability to recognise faces, to be good at that, does that seem to be linked to genetics in some way?
Nic - Yes. There is a substantial genetic component. It is substantially heritable. That in itself isnít unusual. That is generally found for abilities in lots of different areas. What is unusual is that the genetic influences on it donít seem to be related to the genetic influences on other things. So in general for example, there aren't genes for reading or genes for maths. Specifically, all of the genetic influences in those areas tend to be shared between them. It tends to be the same genes which are influencing different areas.
Kat - So, there are the same genes that are basically making you good at learning or good at concentrating or good at focusing or something like that and that enables you to have good ability across all these areas.
Nic - For example, yes and undoubtedly, itís genes affecting lots of different things in lots of different ways. But they're overall effects in aggregate is shared between lots of different areas. With face recognition, we find exactly the opposite. So again, there are considerable genetic influences on these things but they seem to be unique to that area. So, the genes that generally affect abilities in other areas almost donít affect face recognition at all. There is some overlap but very little. Almost all of the genetic influences on face recognition donít seem to influence peopleís ability in any other area.
Kat - So, what does this mean? Does this mean that the face recognition bit of our brain has evolved separately from our other abilities? How does this all fit together?
Nic - Thatís a very interesting question. There has been a lot of suggestion for a lot of different reasons that face recognition is separate from other abilities and that may have been because it evolved in response to different selection pressures. For example, people think that obviously, being able to tell a friend from a foe easily is likely to be quite a strong survival skill and particularly in a very social species like ours. And so, there's been a suggestion that that makes it particularly important thing which therefore may have evolved independently from other things.
Kat - So, does this help to explain why I'm good at science and I can't remember faces at all?
Nic - Quite possibly, yes. And of course, itís very possible to be good at both. But there is very little relationship between them...