Humans are genetically designed to consume meat. In countries where meat consumption is low - such as India, there’s large portions of the population with intellectual and developmental disabilities which could be prevented largely if more meat was consumed. India has approximately 500 million of these people. Iodine is an essential nutrient most commonly found in meat, and especially seafood. When humans, especially those who are young do not get enough of this essential nutrient, it can lead to intellectual disabilities & developmental issues - it can even cause endemic goitre.

Of course, in most developed countries vitamins, and iodized salt is commonly available, so vegans are able to maintain a healthy and functioning brain - but poorer, and underdeveloped (and especially remote) countries and areas do not have this luxury - So yes, scientifically humans require meat.