Deep in the dusty red expanse of the Kalahari desert, scientists have discovered the world's next great reality television stars.
These creatures would put the contestants of "The Bachelor" to shame. They live in one of the animal kingdom's most cooperative societies — in meerkat mobs (no really, that's the collective noun) offspring are raised communally, even though only one alpha pair of parents is allowed to breed. But that makes the competition for alpha status exceptionally fierce. Dominant females will eat the young of other meerkats to ensure that only their own descendants survive. They may also exile offending subordinates from the colony, forcing them out on their own into the harsh and unforgiving desert.
And in case it wasn't clear that these critters really aren't here to make friends, one of the first things young meerkats learn how to do is eat venomous scorpions alive.
But, whereas on reality television the metric for success might be, say, the ability to create a three-course meal using nothing but rutabagas in under an hour, or mastery of the "smize," in a meerkat mob what matters is weight. Larger, heavier females get to reproduce, and everyone else must resign themselves to a lifetime of babysitting.
"There's very strong selection on females to get to the breeding position and they consequently compete like hell to get there," University of Cambridge behavioral ecologist Tim Clutton-Brock explained. Since the heaviest female typically takes over breeding when the dominant female dies, this means that everyone in the mob is constantly jockeying for position at the front of the weighs-the-most "queue," as Clutton-Brock put it (he's British).
All that infighting makes them acutely sensitive to one another's weight. In a study published Wednesday in the journal Nature, Clutton-Brock reports that meerkat females will adjust how much they eat in response to the growth of those around them, gobbling up extra calories in an attempt to stay larger than the runner-up.
Working with a wild Kalahari meerkat mob that was already used to human presence, Clutton-Brock raised the weights of some of the smaller, younger females by feeding them hard-boiled eggs (the meerkat equivalent of muscle milk) twice a day. These were the "challengers."
In response, siblings of the challengers started eating more as well — even though they had to go out and search for their own food, rather than being fed by the researchers. By the end of the experiment, the growth of almost every sibling was proportional to that of her fed challenger, allowing heavy females to maintain their status.
But uneasy lies the head that wears the crown. Even once they've reached the top, females must be careful to maintain their physical dominance. After ascending to the breeding position, the alpha female undergoes three months of rapid weight gain, eating everything she can get her tiny teeth on. This growth spurt is especially drastic when the next-biggest female is close to her in size.
The payoff for all that work is being allowed to breed. According to Clutton-Brock, female meerkats will give birth to as many as 81 pups in their lifetimes. Make of that reward what you will.