Washington, Mar 27 : Just like men can use fast cars or showy clothes to impress the ladies, male Amazon river dolphins, or botos, carry natural objects such as sticks and rocks, sometimes throwing them or thrashing them against the surface, to lure females, says a new study.
In dolphins, the males are usually the attention seekers carrying a branch or similar flotsam in its mouth. Researchers said that such "player" behaviour is a first to be noticed in aquatic mammals and, in case of land mammals, it was seen only in chimpanzees and humans.
These new findings of the study led by Anthony Martin, a behavioural ecologist and population biologist at the University of St. Andrews in Scotland will help show that humans are "not as different from other animals as some might like to think."
Botos or pink river dolphins (Inia geoffrensis), live mostly off fish in the Amazon River basin, with the occasional turtle or crab and often look-like playing with items such as sticks or lumps of hard clay, thrashing them against the surface of the water or tossing them with flicks of their heads.
When scientists noticed that three botos that held objects in their mouths were all adult males, it led them to doubt it as just play. Thus, the researchers carried out hundreds of subsequent observations of dolphins.
Thriving and working in the flooded Amazon forest was difficult, with investigators having to overcome things "like the heat and humidity, which destroys electronic equipment; opacity of the water, which is like milk coffee, you can't see underwater; and the insects and fungi that busily turn our floating lab home into mush," Live Science quoted Martin, as saying.
It was found that the overwhelming majority of those carrying items were adult males, which are larger and pinker than females.
"It's particularly interesting that the complexity of this behavior in these dolphins is considerably greater than that in chimps. Chimp males break off branches, thrash them around and make a lot of noise to show off how macho they are - bit like blokes with big motorbikes and Ferraris, I guess. Botos, however, are much more subtle, and often use their objects in what appears to be a ritualistic way," said Martin.
They observed that the males usually held objects when there were adult females present.
"This species has a mythical reputation for enchanting and seducing women in Amazon communities, and you could believe that they really are enchanting their own females with this object-carrying behavior," said Martin.
The scientist added that aggression among males, like biting or striking another dolphin with the head or tail, was directly linked with object-carrying, and was possibly linked to access to females.
Despite the scientists think they saw some females carry objects, "it's possible some of these 'females' were actually pre-adult males, because some such males are the same size and colour as some adult females. Even if these were females, the number of examples of females carrying objects was tiny, and in any animal population you can expect to find some individuals who do things different," said Martin.
Martin noted this behaviour was found in populations of botos that have probably been geographically isolated from each other for millions of years.
"It is therefore either ancestral to them all and therefore millions of years old or has evolved independently in each case," Martin said. "Either way it does appear to be deep-rooted in their behavior and passed from one generation to the next. Some would argue that this is culture."
The findings of this study were detailed online in the journal Biology Letters.