In the human situation reproduction is sexual. Albeit not always thoughtful, many aspects of human life are motivated by sexual reproductive drives. In fact, from Descent of Man Charles Darwin wrote, "Man scans with scrupulous care the character and pedigree of his horses, cattle, and dogs before he matches them; but when he comes to his own marriage he rarely, or never, takes any such care. He is impelled by nearly the same motives as the lower animals, when they are left to their own free choice, though he is in so far superior to them that he highly values mental charms and virtues."

It seems that human sexual drives are optimally designed so that reproduction will primarily be successful and plentiful, as is the case with most animals. Moreover, it is indisputable that human sexual drives significantly motivate mankind's behavior by increasing the human population beyond rational numbers. The increased human population then motivates increased environmental adaptation and dispersion. Only recently have some technological cultures socially evolved to control their reproductive proclivity so that a greater share of resources can be given to their people and significant social/economic prosperity achieved. However, world human overpopulation has already occurred and most societies are at risk.

The totality of the evolutionary process involved in creating all life, humankind, and thoughtful scientific advancement is more than just biological evolution. It is the combination of cosmic, biological, and social evolution and the combination seems to propel all matter, life, and even ideas. Thus, the original energy of the universe relentlessly directs humankind, along with everything else, through time, and space using the mechanism of universal evolution.

Cosmic evolution, which gave rise to matter and the subsequent biological and social evolution of mankind, has inherently created or directed within people the basis of human behaviors. Humankind's ability to thoughtfully adapt, disperse, and recently, in some cultures, even thoughtfully reproduce has helped people better fit into changing environmental situations and survive. Consequently, intelligence is an obvious successful evolutionary adaptation and survival strategy for humans. Without intelligent planning and the social ability to team together and form a society of various capabilities which, as a unit, competes with natural forces, mankind would be no better than an isolated genius or a colony of bees. Neither has been able to develop space flight, either because of isolation or due to a lack of intelligence.

Natural selection has determined that Homo sapiens adapt to their environment in many ways, but significantly, intellectual adaptation has allowed humans to prosper over competing animals. Somewhere within the last two million years there has been a shift to cooperative hunting, tool making, and gathering, with accompanying requirements for a high level of intelligence, language, and social organization. This attended the rise of the modern human species. People were then found walking upright to better use their hands and weapons; they had opposable thumbs so tools could be fashioned and fire's lit; they organize in teams to hunt, gather food, or raise their young; and they explored the unknown with their "mind's eye" so they could invent something to give them an edge. Most other animals have specialized anatomies designed to do many things better than humans. However, with the exception of upright posture and an opposable thumb, the abilities that give mankind the edge reside in the human brain. It has evolved to be more powerful than the other animals allowing people to imagine, think, and communicate with language. Thus, humankind has the most social cooperation as well as the best tool making abilities and inventive capabilities of Earth's animals.

Therefore, with thoughtful adaptation, dispersion, the ability to reproduce wisely, and the ability to team together, mankind exists with relative success. However, partly due to human sexual drives, that are not always thoughtful, people have overpopulated the Earth, fought countless terrible conflicts, and placed great stress on the resources necessary for their survival.

Darwin's comments on overpopulation were evident even in 1871, "Man, like every other animal, has no doubt advanced to his present high condition through a struggle for existence consequent on his rapid multiplication; and if he is to advance still higher, it is to be feared that he must remain subject to a severe struggle." Darwin confirmed this again by writing, "Man tends to increase at a greater rate than his means of subsistence; consequently he is occasionally subjected to a severe struggle for existence, and natural selection will have effected whatever lies within its scope."

In a hostile environment, composed of increasing numbers of competitive human identities, mankind has survived best by using intelligent specialty teams working as a creative unit. Historically most people have been forced to struggle militarily, economically, personally and in countless other ways to survive. Eventually, in the struggle for resources and dominance, societies evolved to develop advanced specialty teams. Among the more important are: educational, medical, religious, scientific, artistic, military, economic, musical, agricultural, governmental, and industrial specialty teams. In the twentieth century, the more creative specialty teams generally helped advance a greater understanding of the world and the universe. Governmental organizations today are beginning to have the ability to protect the planet, and disperse its' life when threatened by cosmic catastrophe. In no small part this is a direct result of the scientific advances brought about by socially evolved creative specialty teams employed by governments during two World Wars and the Cold War.

In 1871, although man's intelligence had not yet propelled him into space, Darwin concluded on the final page of Descent of Man, "...with his god-like intellect which has penetrated into the movements and constitution of the solar system-with all these exalted powers-Man still bears in his bodily frame the indelible stamp of his lowly origin."

In the twenty-first century, although mankind seems to have invented interplanetary flight and nuclear explosives, the lowly origin of the species, reflected in the human appearance and evolutionary/social history, might in some ways prevent greater accomplishments. Darwin's prophetic conclusion could result in humankind not being as important as it projects itself to be, or maybe humans will succeed in their unique biological niche and Man's, "...god-like" intellect will overcome "... his lowly origin."