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Family matters: why it's important to recognise kin

Family matters: why it's important to recognise kin

作者:厍奖  时间:2019-03-07 14:10:00  人气:

By Andrew Holmes Family. It’s an odd thing, isn’t it? A bunch of people you can adore or absolutely hate but who you’d still probably do anything for. People you can have nothing in common with except other relatives. You only have to look at culture through the ages to see just how important kinship is. Hamlet’s first words are “A little more than kin, and less than kind”, a fitting introduction to the family tragedy that unfolds. From Oedipus the King to Blood Brothers, kinship appears again and again, and a case of mistaken identity can make for fine comedy or delicious tragedy. Why do relatives matter? In humans it’s obvious: your family often consists of a group of people who are there for you no matter what. They provide support and encouragement, give advice and learning and do their best to help you have the best life possible. In non-humans, kin can group together for protection or foraging, can cooperatively care for young, or can simply choose not to fight one another. It doesn’t always happen – siblicide and infanticide are common in many species – but there are many occasions when knowing your relatives can help. In particular, being able to recognise your relatives helps prevent matings between close kin, and because relatives have genes that are identical by descent, aiding a relative’s reproductive success can improve an individual’s own genetic fitness, provided that the costs of giving help are outweighed sufficiently by the benefits gained. It may not always be beneficial but there is evidence that under certain conditions kin recognition and the behaviours that result from it can be advantageous. Whilst self will normally come first, the closer the relative, the more likely you are to share genes identical by descent and therefore the more you could gain from helping them. It’s rather like the Arabic saying: “I against my brother, I and my brother against our cousin, I, my brother and our cousin against the neighbours, all of us against the foreigner”. Recognising relatives is often an easy task for us humans. Our highly social lifestyle and advanced vocal communication mean that it’s rare to meet a relative without being aware of it, and we can normally remember those relations we’ve been introduced to before. It’s a rare situation, but have you ever spotted a resemblance between two people and realised they were related before being told? Or have you noticed similarities between your own family members, a shared physical or behavioural trait perhaps? Depending on who sees us, my brother and I could be twins or adopted. One particular observer even claimed that we share a nose but nothing else. But how do non-humans recognise relatives? A lot of the time it can be a simple rule – those present in the nest with me are related to me, everyone else I should treat as being unrelated to me. In many situations this mechanism no doubt works; it enables the recognition of the closest relatives, parents and siblings. But what about those situations where there is no nest, no initial period of cohabitation that allows relatives to be learned? What about situations where previous litters have already left the nest? Close relatives could easily be encountered that simply weren’t present when the young were taking names. This is where I find kin recognition really comes together and gets interesting, because there is evidence that many different animals can recognise their relatives, despite never having encountered them before. Indeed, there is evidence of kin recognition in all the major groups, from mammals to fish, birds to amphibians, as well as insects, plants and single-celled organisms. I’m sure that I’d be unlikely to recognise most of my relatives had I just encountered them in the street and never been introduced to them, shared nose or not. Yet certain animals are able to recognise unfamiliar kin and change their behaviour towards them accordingly, choosing not to fight, not to breed, to nest or group together or simply to avoid each other. Kin recognition can occur under different situations, for different reasons, and is perhaps often undetectable. We don’t even know much of the time whether the behavioural differences we observe are due to a mechanism designed for recognising kin or whether it is simply part of an overall recognition mechanism reaching from self through the different levels of relatedness to group recognition and onto species recognition. Debates flare up about particular issues or new bold claims for or against it and arguments linger about definitions for mechanisms,