Getting Sick Of It: How Caterpillars Try To Cheat the Group Protection System (and Fail)

Group protection is probably one of the most basic goals of social interaction between organisms. As the old adage goes, "there's always safety in numbers". But what if this social theory is wrong? How do you explain that? 

A recent study looked at a species of caterpillar called Pieris brassicae which when attacked by a predator will regurgitate its last meal, producing a foul smelling compound that often causes the predator to avoid the caterpillar. However, by doing this, the caterpillar loses out on valuable nutrients from the meal and often experiences stunted growth as a result. As a result, the caterpillar only employs this defensive mechanism when it is absolutely necessary because the individual cost to doing so is very high.

For a previously unknown reason, it has been shown that forming groups of these caterpillars for the purpose of protection does not result in a greater chance of survival on an individual basis. To explain this, the study looked at the individual behavior of the caterpillars alone and in groups. What they found was that when in a group, the caterpillar's rate and volume of regurgitation decreased significantly as opposed to in an isolated environment. This shows that the caterpillar is able to modulate its response based on if there are other individuals who are capable of performing the same act. This also shows that each individual reduces their contribution towards group protection, which in this case is enough to cancel out the supposed benefit that group formation gives for fitness. 

The full article can be read at http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2012.01770.x/full

-Eric Baeuerle

Other species have best friends too!

Turns out humans aren't the only species that benefit from making friends with non-kin!  As humans, we benefit from having close friends in that they help us manage stress which can help lead to a longer life.  Turns out that, in other species, having a close friend can actually be an evolutionary advantage: organisms with close friends are more likely to reproduce and are better at fighting diseases.  Some male chimpanzees spend significantly more time with certain other chimpanzees; they groom each other, share meat, and even hunt together.  Some female baboons groom certain other baboons much more than others and are more likely to help out a baboon that has recently groomed them.  If a fight ensues shortly after the grooming, having that extra baboon friend to help out could almost certainly mean the difference between life and death.  These baboons that form close bonds have more surviving offspring and live longer.  These results have also been found in other monkeys, lions, elephants, dolphins, and rodents.  It was recently discovered that female horses in New Zealand tend to form friendships with non-relatives in order to keep aggressive stallions at bay.  Mares risk their lives to help their friends with the expectation that the same help will be given if they ever need help with aggressive stallions.  Researchers are currently trying to understand how this occurs physiologically.  Thus far, they have pinpointed both a particular social-bonding hormone and oxytocin in monkeys; monkeys with more of these hormones are more generous.  Hopefully, further research in this area will help us to understand how human's tendency to form such close bonds with unrelated individuals evolved.

Here's the link to the article, check it out!

http://www.sciencenews.org/view/feature/id/339326/title/Furry_Friends_Forever

-Cristina Terhoeve

Eusociality of termites

An article was very recently published called "Brood care and social evolution in termites." The full text of this article is still not yet available at Rice, but the study presents some intriguing findings. The evolutionary community has always assumed that cooperative brood care was a necessary component for eusociality and a driving force of social evolution. However, this study looked at four different species of termites and found that cooperative brood care was common in only one of them. It appears that the evolution of eusociality in termites may have actually been driven by increased defense!

The abstract of the article can be found at http://rspb.royalsocietypublishing.org/content/early/2012/03/01/rspb.2011.2639.abstract

-Elizabeth Richardson

Is there an evolutionary basis to being nice to old people?

Humans, by nature, are an altruistic species. Unless we're affected by a mental illness, most of us feel bad about doing bad things and good about doing good things. We live by morals and we help our own, and this is especially true regarding our treatment of our elderly. We do our best to make sure Grandma and Grandpa are comfortable and taken care of, if not in our own homes, than with trusted medical staff. We don't always succeed in getting them the best treatment, but we try our hardest, with the best intentions. The topic on my mind today is, is this exclusively a human behavior, or is it a 'thing' across the animal kingdom? And if so, why? We have seen in class that animals have developed altruistic behavior in order to help relatives reproduce, but that is a different scenario. I'm not saying we should neglect old people; that would be terrible, but what, if it exists, is the advantage of altruism toward members of the species that are no longer reproductive?

After Googling around, I stumbled upon the expert opinion of evolutionary biologist Dana Krempels, who confirms that this behavior is indeed rare. Humans live in relative luxury and have no natural predators, so we can afford to practice behaviors that would be maladaptive in a hostile environment where the danger of predators lurks around every corner. Interestingly, though, in some cases altruism towards the elderly does develop in animals that have a sophisticated social order. Read more about it here.

-Mindy MacKay

The Evolution of Kissing

Unless you're this guy, you probably know that kissing does not make babies. So what, you might wonder, caused kissing to evolve as part of the human sex act?

Well, researchers suspect that kissing evolved as a means to immunize women against illness prior to pregnancy--read the full article here.

-Mindy MacKay

The Evolution of Sociality in Primates

Why are primates so social?  Also, more specifically, why are humans so social?  With the exception of primates, very few mammalian orders contain species that exhibit social behavior.  Shultz et al. have provided several clues as to why primate social behavior is so different from other mammalian orders by examining data from the past 74 million years!

They discovered that the most crucial step towards sociality occurred when primates began to become diurnal rather than nocturnal.  When primates were nocturnal, they tended to be solitary foragers that could avoid detection by hunting quietly in darkness.  When primates began to hunt during the day, their activity became more recognizable to predators simply because they could now be detected more easily in the light.  Primates who travelled and hunted in packs were more likely to survive, and thus more social primates evolved by means of natural selection.  These primates were less likely to become victims of predation because each predator would only kill one or two primates in a group and, as a result, the vast majority of the organisms in the group would survive each predator attack.  Also, having more primates to compete in each predator attack increases the likelihood that the predator will either die or retreat.  The research suggested that these social groups were only loosely bound: members could come and go as needed.  Behavior similar to this is present today in lemurs.  Primates did not begin to form small groups with close social links until millions of years later.

Unlike all other primates, humans have the ability to cope in numerous different social settings.  Over time, we have functioned in many complicated social settings: monogamous versus polygamous societies, nuclear family versus extended family groups, various work settings, etc.  Our social flexibility both in groups and in wider society is unmatched by any other species.  Shultz et al. discovered that this is a result of increased brain power (humans have more brain power than any other species).  This makes perfect sense: increased brain power allows us the ability to adjust to changes in our environment.  No other organism has the mental complexity to surmount this obstacle.  How cool is that?

Link: http://www.sciencedaily.com/releases/2011/12/111220205212.htm

-Cristina Terhoeve

Share the Love: A closer look at polygamy

When you’re little, everything seems so simple. You grow up. You fall in love. You get married. You have a family. At least that’s what I thought life was like, but I would soon come to find out that, for better or for worse, nothing in the world is that straightforward. “Alternative” types of relationships are getting increasing media attention. TLC broadcasts Sister Wives, a reality television series featuring the polygamist Brown family, and open relationships and open marriages are not unheard of. But such does not come without criticism. In his book, Opening up: a guide to creating and sustaining open relationships, author Tristan Taormino claims some of the most common criticisms to polygamy include “the monogamous person is being taken advantage of,” and “the non-monogamous person wouldn’t be doing this if she really loved the monogamous person”. Words like “sexist”, “coercive” and “patriarchal” have even been thrown around, and many groups, including numerous churches, claim that polygamy is an “abomination”. But what makes it so detestable? Can polygamy really be considered unnatural?

No. In fact, it’s quite the opposite. Cases where polygamy has naturally evolved are widespread and incredibly diverse. A vast number of species, we know, are promiscuous, meaning any male will mate with any female. But there are also many polygamous species, where a single individual maintains relationships with multiple mates. LiveScience published a list they call the “Top 10 Swingers of the Animal Kingdom”, species that break so-called norms. As one might assume, included on the list are lions, which are largely known to live in prides in which few males have mating rights to a large number of females. But also making appearances are (among others) walruses, African blue-headed lizards and bronze-winged jacanas, a tropical species in which females maintain a harem of males to raise her many clutches of eggs. Although not polygamous like the previously listed species, bonobos also make the list for their unique approach to sex. These promiscuous primates have been known to form short-term heterosexual, homosexual and even incestuous unions, and live in relatively peaceful societies. The frequent sex in bonobo societies is thought to “strengthen social bonds and resolve conflict”. Taking a look at the animal kingdom quickly shows us that monogamy is not the only answer, and promiscuity and polygamy are far from unnatural.

Now for my two cents. Individuals cannot choose to be a certain way, just like species cannot choose to evolve in a specific direction and what works for some is not necessarily what’s best for others. So ignore what your neighbor’s doing. Every human, just like every species, is unique and has their own way of doing things. That’s what makes life so fascinating.

The full LiveScience article can be found at: http://www.livescience.com/12963-top-10-polygamous-animals-bonobos-hyena.html

-Elizabeth Richardson