Chris Anderson-am I being too harsh? You have conducted controlled studies with Bradypodion. Maybe I'm more cynical than I should be.
Yeah, you're being too harsh in this case I think. This is an excellent example where interpretation of the findings of a study based on the media coverage of that article is misleading. I highly recommend anyone interested get a copy of the actual publication (
http://www.sciencedirect.com/science/article/pii/S0003347213005186) and read it rather than judge it on the media coverage, which is always sensationalized and distilled to what they think is catchy and will grab headlines. I suspect anyone without institutional access will not be able to download the full publication, but typically if you contact the corresponding author (they are denoted by a symbol of some type after their name in the author list and their contact information is almost always listed), they are happy to send you a PDF.
Just to dispel a few misconceptions, however, here are a few comments:
First, while the media release is focused on color change in general as the result of the group vs individual rearing, the article itself is more concerned with the outcome (i.e., dominant vs submissive behavior) of social interactions between individuals from different rearing groups. They use color as one measure to quantify the responses of each individual during interactions. They found (among other things) that while aggression level (specific behaviors are outlined in the paper) was not effected by rearing group, that individually reared animals exhibited more submissive behaviors than those raised in groups and that they adopted darker colors as well. We all are fairly familiar with how color relates to dominance and submissive behavior in chameleons, so this should not be particularly surprising given the findings related to submissive behaviors.
Next, despite the generality of the media article attributing the findings to chameleons in general, the title of the paper itself is quite specific emphasizing the particular species and age group: "Effects of early social isolation on the behaviour and performance of juvenile lizards,
Chamaeleo calyptratus". The authors do specify that "sensitivity to early social environment may differ between species within lineages, rather than be present versus absent in entire groups" and go on to state that "The potential influence of an individual’s social environment during juvenile life on its success in contests during adult life has yet to be experimentally evaluated."
Additionally, while statements in the media release are provided without citations, such comments include supporting references in the article itself (including those regarding mass hatching, low dispersal ability, and hatchling aggregation).
I think in general Bill's summary of social history effecting future behavior is particularly relevant to this paper, with one of their main conclusions being that "encounters with conspecifics early in life may shape a chameleon’s subsequent behaviour, as it does in many species of endothermic vertebrates." The authors go on to suggest that "The neonates that were reared in social groups (rather than isolation) may have benefited from early exposure to competition from conspecifics, favouring behaviours that enable a lizard to seize a prey item before it is taken by a conspecific; and familiarity with intraspecific agonistic encounters may also have facilitated an individual’s performance in social tasks." One of the most important points of this study, however, is that early social experience does not only effect behavior in "higher" vertebrates like birds and mammals, but that reptiles too experience social learning/conditioning.
Chris