A number of genetics studies have claimed in their findings that modern humans and Neanderthals have had sex some thousands of years ago. They said that the intimate relationship was formed between the two populations at the time when they roamed around the planet.

However, a recent study taken out in Mexico has refused to accept findings of the studies. Study researchers were of the view that they have carried out studies on monkeys, and on the basis of the same, they can affirm that such relationship was formed.

In addition, bones found of the two species have not dictated of the same. In order to reach at the above given result, the study researchers assessed hair samples as well as blood samples of two species of monkeys.

Two species of monkeys were mantled howler monkey and black howler monkey. Liliana Cortés-Ortiz, who is evolutionary biologist, said, "The implications of these results are that physical features are not always reliable for identifying individuals of hybrid ancestry".

Study researchers said that they have not been able to find any sort of strong link in fossil record. That is the reason that they have said that the relation cannot exist, but still the opinion about the same is not uniform.