The apes are social animals, and also imitative animals. The ape-like forbears of man would unite for safety and for society, and, being imitative, would observe and copy any invention or discovery due to lucky accident or to the sharper wits amongst their number.
Like the lower animals, they would play together, feed together, fight in companies, defend or rescue their young, and post sentinels to watch for the approach of danger.
Long before man had thought of any ghost or God, some rude form of order and morality would exist in the families and tribes of men, as some rude form of order and morality exists to-day amongst the wild elephants, the bees, the deer, and other creatures.
I once saw two horses fighting in a field. A third and older horse came up and parted them, and then drove them away in opposite directions. So in the earliest human tribes would the leaders prevent brawling and exact obedience.
Partly from such action, and partly from the training of the young, would be formed the habit of resenting and of punishing certain unsocial acts which the herd or tribe felt to be opposed to the general welfare.
One of the first faults man would brand as immoral would be cowardice. One of the earliest moral laws would, perhaps, resemble the Viking law that men who proved cowards in battle should be buried in the swamp under a hurdle.
Imitation, habit, natural selection, and the love of approbation, would all tend to fix and improve these crude customs, and from these simple beginnings would grow up laws and morals and conscience.
Very likely the earliest human groups were family groups, or clans. These clans would fight against other clans.
The next step may have been the union of clans into tribes, and the next the banding of tribes into nations.
At present men are mostly united as nations. Each nation has its own laws, its own morality, and its own patriotism, and the different nations are more or less hostile to each other; as formerly were the tribes or clans.