Chimpanzees are the humans' closest living relatives sharing almost similar DNA, but still there are differences. A new study by researchers from the Kyoto University has showed evidence that the human brain is far bigger than a chimpanzee's brain.

Using 3D ultrasound imaging, experts analyzed the brain's growth of wombs in two pregnant chimpanzees during their gestation period. The gestation period of humans is little longer with 38 weeks than the female chimpanzees having either 33 or 34 weeks of gestation period.

This is the first time that researchers have actually measured the size of the chimpanzee brain as the wombs grew and compared it with the images of human fetuses. They found that the differences in the brain growth of both the primates begin after several weeks of gestation.

The brain growth was increasingly faster during the initial stages of the womb in both the species. While the brain growth stopped after 22 weeks of gestation and started leveling in chimpanzees, the experts noticed that the brain growth of the human fetus continued for another two months. As the brain development emerged much faster in humans, the differences in the two primates occurred even before the birth of the species and after that, according to a report in phys.org.

The new findings have been part of the research work that was done last year to track the brain growth of chimps aged between six months and six years and compare it with the human brains.

In the previous study, experts suggested that the brain portions like forebrain which are significant to perform cognitive functions such as decision-making and creativity are immature at birth. But they are planning to study further in order to analyze the fetal development in the forebrain so as to understand the behavior of humans.

"Elucidating these differences in the developmental patterns of brain structure between humans and great apes will provide important clues to understand the remarkable enlargement of the modern human brain and humans' sophisticated behavior," said study co-author Tomoko Sakai, of the Kyoto university, according to phys.org.

The findings of the study are published in the journal Current Biology.