American scientists from NY university found a relation between the duration of yawning and the size of the mammalian brain, this study was published in ” Biology Letters” magazine. According to the study , animals with few cortical neuron yawn for a shorter duration than mammals that has more advanced nervous system . this result was reached after analyzing 29 videos for human and some animals like mice,cats, wolves, hedgehogs and elephants.
It turned out that monkeys yawn for 6 seconds longer than other mammals as it have 12 million cortical neurons, the same for African elephants , the least duration was for mice, as it yawn lasts about 1.5 second. Scientists said that yawning increases blood flow to the brain and cools it down, which means that the bigger the brain is, more time is needed to cool it down.