Behaviour

The Cuckoo Underworld

14 January, 2015 by

Most birds make nests, and spend their time foraging to feed and care for their chicks. Cuckoos, on the other hand, don’t waste their time with any of that, they simply lay their eggs in another bird’s nest and let them do all the heavy lifting. This might sound like the easy option, but in fact cuckoos have made a whole lot more work for themselves trying to evade and deceive their neighbours. When cuckoos succeed in their trickery, their unsuspecting host suffers, producing fewer young that year and wasting time and energy. So, evolution has pitted host birds against cuckoos, with each side developing increasingly sophisticated techniques to try and get their own way. Host birds mob potential attackers, while cuckoos use mimicry to avoid detection, and threaten defectors with serious consequences.

Cuckoos are famous for taking advantage of their unsuspecting neighbours; laying eggs in their nest and leaving their unwitting host to raise the chicks. The world cuckold, used to refer to the husband of an adulterous wife, originates from the cuckoo bird. There are over 50 species of parasitic cuckoo in the family Cuculidae; some are generalists who will lay their eggs in any available nest, others specialise in one or a few ‘host’ species, but all are engaged in an evolutionary battle with the species they parasitise – an arms race, if you will. Species parasitised by cuckoos are at a disadvantage – in the best case they are merely wasting resources raising an unrelated chick, in the worst case the chick will hatch early and push out the other eggs in the nest, meaning that the unlucky bird in question loses an entire clutch. In each generation, therefore, natural selection will favour host birds that are able to avoid parasitism. The birds might evolve to be more discerning, for example, identifying the appearance of cuckoo eggs and removing them, or selecting nest sites that are more difficult for the cuckoos to access. Equally, in each generation the cuckoos that are most successful in deceiving and parasitising their neighbours will produce more offspring and their traits will be favoured by natural selection. Cuckoos might evolve eggs that more closely resemble those of their host, or very rapid egg incubation to ensure their chick hatches first. Ultimately, neither species wins, with evolution demanding increasingly sophisticated tactics for successful parasitism in cuckoos, and traits to thwart parasitism in the host species.

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Couples Sleep In Sync

17 October, 2014 by

Love it or hate it, sharing a bed with someone is the norm for most adults in a relationship, but how well we sleep together can have a profound effect on our mood, our relationships and the rest of our lives. A new study presented at a recent SLEEP conference suggests that sleeping couples sleep better together when the woman is more satisfied.

It has previously been reported that divorced and single people experience more sleep disturbances and generally poorer quality sleep than couples, but it seems that the quality of your relationship might also influence how well you sleep. Research presented at SLEEP 2014, the 28th annual meeting of the Associated Professional Sleep Societies, suggests that how well you sleep with your partner may be a reflection of the quality of your relationship. According to lead author Dr Heather Gunn from the University of Pittsburgh, “the sleep of married couples is more in sync on a minute-by-minute basis than the sleep of random individuals”, suggesting that our sleep patterns are influenced not just by where and when we sleep, but with also with whom we sleep.

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Rat Regrets

19 June, 2014 by

We like to think that our more complex emotions are uniquely human, although researchers continually thwarting that belief with science. This week, another of our emotions came under threat – regret. Nobody has ever demonstrated regret in another non-human animal. Until now. A study released this month in Nature claims to have found evidence that rats are capable of feeling regret, a complex emotion distinct from mere disappointment.

Disappointment is when we recognise that we didn’t get as much as we expected, whereas to regret is to recognise that our actions are the reason behind this – that an alternative action, a different decision, would have produced a better outcome. In this study, researchers forced rats to choose between waiting for a particular reward, or moving onto the next reward that may come with an even longer wait. This is exactly the type of situation we might expect rats to feel regretful about, but are they smart enough to feel such a complex emotion?

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The Long Winter Sleep: The Biology of Hibernation

12 December, 2013 by

At this time of year, as the nights begin to draw in, and a chill appears in the air, the idea of simply curling up in a warm spot and sleeping through the winter months is very tempting. Unfortunately for us, Humans are not among the species which undergo hibernation. However, many other mammals reduce their activity levels during the winter, and a few undergo full hibernation, biochemically altering their metabolism to wait for more favourable conditions.

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Can Chickens Change Sex?

15 May, 2013 by

Question:

Not the most pervasive of suburban legends, granted, but it seems to keep popping up. It goes something like this…

Confused Farmer finds Hen is now Cock
The mature hen, Gertie, who had laid eggs the previous year, suddenly stopped, grew chin wattles and started to crow.

So, can chickens really change sex?

Answer:

The short answer – No.

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Selfish Strategies in Cooperative Society

10 March, 2013 by

Social insects show extraordinarily high levels of cooperation, giving up their reproductive opportunities and even sacrificing their own lives to save the colony. The social insect colony is a well-oiled machine, each part has its own key role to play, together forming an intelligent and adaptive society. Most people are familiar with the highly advanced social insects, such as honeybees and leaf cutter ants. Their societies are huge and intricate, and we have gained many fascinating insights from them. However, they tell us very little about how these societies evolved, or what it meant to be cooperative in a more primitive sense.

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Animal Personality Part II:
The Evolution of Personality

18 November, 2012 by

The field of research into personality and behavioural syndromes in animals has blossomed over the past few decades. With ample evidence for it’s existence, biologists have begun to consider its evolution; what is the adaptive benefit of personality? How are multiple personality types maintained in a population? Why do personalities exist when they sometimes result in maladaptive responses?

All these questions, and any evolutionary questions we might care to ask, make the assumption that personality is heritable. Without heritability, personality cannot be passed from generation to generation, and cannot be subject to natural selection. There is now plenty of evidence for high heritability of many personality traits in animals, although there is also an important influence of the environment too. Heritabilities estimates vary, from 0.22 – 0.61 in wild great tits, 0.32 in social spiders, 0.54 – 0.66 in humans and 0.2 – 0.8 in dumpling squid. These genetic influences may in part be reflected in brain morphology; one study in humans found differences in brain structure relating to neuroticism, conscientiousness, and extraversion. More neurotic people have a smaller total brain volume and a smaller frontotemporal surface area, whilst extraverts have a thinner inferior frontal gyrus.

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Animal Personality Part I:
Individual Differences

4 November, 2012 by

To even the most casual observer, it is clear that people are not homogenous in their behaviour, and that this goes beyond possible nurture influences such as cultural upbringing. Individuals vary in their behaviour in a consistent manner; some people are generally more aggressive, friendly and adventurous in every aspect of their lives. So obvious is this observation that we even have a word for it – personality. Likewise, anyone who has spent any significant amount of time in the company of animals will almost certainly acknowledge that they are not all the same. The extent to which this is apparent varies from species to species, of course, but the observation is not a revolutionary one. And yet, until relatively recently the concept of ‘personality’ in non-human animals was revolutionary. And it has had to work hard to shake off the criticism of anthropomorphism and pseudoscience.

It was long assumed that animals were infinitely plastic in their behaviour, being able to respond adaptively to all environments. When people actually started to look, however, it became apparent that this wasn’t the case. Individuals showed substantial variation in their responses to certain events and environments, and these responses were not always adaptive. There was a strong correlation however, in the responses of a single individual over time. Personality, you say?

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What Makes Us Human Part IV
Culture and Faith

9 September, 2012 by

What makes us human? Many of the characteristics commonly listed as ‘uniquely human’, are in fact, upon closer inspection, NOT. We are not alone in our use of tools, language or a notion of self. We are not unique in our bipedal stance, our opposable thumb or our intelligence. Our societies seem simple and crudely constructed when compared to those of a bee or a termite. Perhaps there is one thing left, however, that is truly human – art. Surely culture, art and religion are something only humans have constructed? And if that is the case, what is it about humans that led us and only us, to create such a rich array of art and ritual, which appears, in evolutionary terms, to be superfluous to our survival?

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