Social isolation, especially early in life, can be disastrous for birds and mammals. It can result in adults with increased anxiety and stress, worse performance on cognitive tests, and abnormal social behavior. Early social isolation can even have deleterious physiological effects, including a decreased lifespan.
But what about lizards? They were long-assumed to be asocial and behaviorally 'simple.' But more recent research has shown some lizards are devoted parents and mates that can distinguish their kin from strangers and recognize individuals. Many lizards spend the first few months of their lives in the company of their siblings or a family group, where they might learn important life lessons and skills.
To investigate the effects of early social isolation on lizards, Cissy Ballen, Richard Shine, and Mats Olsson of the University of Sydney hatched veiled chameleons in the lab and reared them either in isolation or in groups of four animals.
Not much research has been done on the social lives of wild chameleons, but hatchlings that are born around the same time are known to be briefly aggregate. It's possible that social experiences during this period may be important for their development.
Ballen and her colleagues staged interactions between pairs of chameleons when the animals were two months old. The researchers found the two groups didn't differ in aggression, but chameleons raised in isolation were more submissive than their siblings raised in groups. The isolation-reared chameleons tended to flee or curl into a ball during confrontations with other chameleons, and they adopted darker and less green colors than the group-reared chameleons. The researchers also tested the foraging ability of the animals, and found that group-reared chameleons seized their prey (crickets) faster than isolation-reared chameleons.
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