Introduced Species Summary Project
Human (Homo sapiens sapiens)


Common Name: Modern Human. Other names: "Man," "the naked ape."

Scientific Name: Homo sapiens. Subspecies: Homo sapiens sapiens.

Modern human and Neanderthal skulls
Modern human (right) and Neanderthal skulls.
Photo: produced by Dennis O'Neil

Phylum or Division: Chordata.
Subphylum: Vertebrata.
Class: Mammalia.
Order: Primates.
Family: Hominidae.
Subfamily: Pongidae.

Identification: Ape with bipedal posture. Skin may be various shades of beige, dark brown, or light brown. Has little hair, primarily on top and back of head, which may be blonde, brown, black, or red. Eyes may be brown, blue, green, hazel, or grey. Has opposable thumbs, and nails on the fingers and toes, but lacks a tail. Makes tools and technology. Builds shelters of all shapes and sizes. Some populations are nomadic. The H. sapiens sapiens skull is smaller and more compact and the face is much less elongated compared to the Neanderthal (Homo neanderthalis); the modern human skull has a higher forehead, less prominent brow-ridges and smaller teeth. Modern humans are typically much less robust in body form and skeleton than Neanderthals.

Population Distribution, 1800-2050
Human Population Distribution, 1800-2050
Photo: United Nations Population Division
Original Distribution: Species Homo sapiens is believed to have originated in East Africa, in what is now Ethiopia, about 200,000-300,000 years ago. Subspecies Homo sapiens sapiens, or modern man, emerged about 40,000-130,000 years ago, but solid evidence in this field is scarce and theories are always changing as new data is found.

Current Distribution: Worldwide. Extremely adaptable and intelligent, it has acclimated to nearly every ecosystem through evolutionary and technological means. Has become established on all 7 continents and is beginning to colonize the planet's orbital regions. Primarily found on land; may also be found for short periods on water surfaces and in the air in transports. On land, prefers coastal locations or regions near water sources.

Site and Date of Introduction: (to North America:) First wave, a group from Siberia in Asia at repeated intervals between 40,000 and 13,000 years ago across the Bering Land Bridge to Alaska. Second wave, a group from Scandinavia in 1000 A.D. across the North Atlantic Ocean to Northeastern North America. Third wave, from Europe to the Caribbean in 1492 A.D. which led to mass immigrations thereafter.

Mode(s) of Introduction: (into all new areas of the world:) By foot via natural land passages. Later by boat/ship sometime during prehistory; first record is 7th century B.C. By air beginning in 1904 A.D. By spacecraft beginning in 1961 A.D.

Norman Rockwell's Golden Rule
Norman Rockwell's Golden Rule depicting humans of every race and culture
Photo: United Nations
Reason(s) Why it has Become Established: Extremely adaptable and intelligent, with a penchant for overcoming challenges and barriers, the warm-blooded mammal Homo sapiens has acclimated to nearly every ecosystem through evolutionary and technological means. As a species it has thicker bones, a larger brain, and less pronounced brow ridges than other apes. A very large brain allows for innovative thought and problem-solving capabilities. The head of a Homo sapiens is larger than other modern primates because the skull needs room to enclose this large brain. The evolution of a bipedal posture was pivotal. Erect stance was a very radical anatomical change in the species and required major changes in the foot, pelvis, and vertebral column. The upper legs of a human have very strong muscles allowing it to stand upright. A curve in the spine near the lower back also allows upright posture because the center of gravity of a human is directly over the pelvis. The first Homo sapiens were nomadic hunter-gathers and scavengers. However, about 10,000-15,000 years ago, agriculture was developed, and people were able to settle down, raise crops, and domesticate animals. Once humans were settled, civilization took hold, first in Mesopotamia but soon in Egypt and elsewhere. The species is omnivorous, with teeth and digestive systems adapted to eating both animals and plants. The body is genetically programmed to store fat in times of famine. Humans also have a highly developed nervous system and strong senses, including excellent eyesight. Especially important is depth perception (stereoscopic vision), made possible because their eyes are located near each other. The large brain size and social structure allowed language to evolve, which is essential for cooperative communication. Culture (transmission of accumulated knowledge over generations) was then transmitted by written and spoken language. Humans also harnessed fire. Like other apes, humans have opposable thumbs which allowed the development of tools. The species has a long life span of up to 100 years. Reproduction is mammalian (live birth, of usually one or two offspring after 9 month gestation), and both parents care for the young for about 18 years and guard them fiercely. The species lives in a family social structure, reinforced by emotional bonds, allowing success through cooperation, shared resources, and division of labor. The species also takes care of its elderly and sick populations, which goes contrary to natural selection and is another result of increased brain capacity and development of emotions.

Ecological Role: Primarily a predator species. Through intelligence and technology, has successfully eliminated threat by all natural predators (large carnivores), other than disease. Impacts all stages of the ecosystem in countless ways via agriculture, water use and redirection, airborne pollutants, etc. The species has become adept at science and technology, to the point of decoding its own genome and experimenting with genetic manipulation of its own and other species. Medical developments, including reproductive technologies, have increased the lifespan and quality of life for individuals of its own and other species. Actions are causing the extinction of other species on the planet at the rate of 30,000 per year.

Lascaux horse
Cave painting, Lascaux, France
Photo: AMNH
Benefit(s): Human intelligence and innovation has allowed it to become the dominant species on the planet. In this role they are caretakers of many other species. Some make the effort to protect the environment and choose not to predate certain species, finding alternate sources of nutrition. Some have learned genetic manipulation which has prevented the extinction of many species. Biological knowledge has also led to achievements in medicine and health, benefitting both humans and other species. Human consciousness has led to the development of art, as well as cultural beliefs in a deity or deities and the formation of moral judgement and ethics, which lead many of the species to act responsibly. The human capacity for learning and its insatiable quest for knowledge leads to ever-increasing studies and it is possible that the intelligence of this species will find a way to solve the ecological problems of its own making.

Threat(s): Humans are an extremely well-adapted, successful species and in becoming dominant they have crowded out and assumed resources from many other species, particularly large mammals which require large amounts of resources and a large range to survive. Humans are greedy by nature, liking a large home range and a wide variety of food resources. They are also unnecessarily wasteful. Overpredation is a large problem and has led to the extinction of many other species. Those that remain do so in terribly low numbers that can be counted. In addition to taking existing resources, human technology and population size contribute large quantities of pollutants which lead to toxicity of remaining resources including air, water, land, soil, and prey.
World Population Growth, 1750-2150
World Population Growth, 1750-2150
Photo: United Nations/Population Reference Bureau
The consequences of this species cerebral growth and resulting intelligence have been enormous. Cultural evolution has resulted in Homo sapiens sapiens becoming a species that could change the environment to meet its needs and not have to adapt to an environment through natural selection. Effects have been devastating. As a direct result of human changes to the environment, the extinction rate of other living organisms is 50 times greater than normal. Such changes include habitat destruction and chemical pollution, destruction of tropical rain forests, and disruption of the atmospheric gas balance, spread of disease, and introduction of foreign species into new environments. This extremely territorial and emotional species is prone to anger and violence, often resulting in the outbreak of warfare on an ever-larger scale. Human intelligence and collective knowledge in the areas of chemistry and physics have led to the development of atomic and nuclear bombs, which if used threaten the existence of life on the entire planet. Biological knowledge has led to the capacity for genetic manipulation, and carelessness or error could lead to biological devastation via the development of "superbugs" or genetically modified species becoming invasive. Additionally, this species has become so numerous and so dominant that it has even reached the capacity to affect the world climate via global temperature change, destroying the ozone layer, and affecting global weather patterns. The recent population explosion of Homo sapiens sapiens is possibly the most devastating crisis in the history of life.

Control Level Diagnosis: Highest Priority.

Control Method: It is believed that the sheer numbers of this species will bring the planet to its carrying capacity and reach critical mass very soon, if it hasn't already. As with all dense populations, disease epidemics are expected to increase in frequency and intensity, and a worldwide plague or resource crisis will cause widespread casualties. Self-imposed population control measures may become necessary. Yet this species will likely never be entirely eliminated except by its own self-destruction. It is hoped the species will develop the intelligence level to control the consequences of its own actions. (If all else fails, everyone could just join the Voluntary Human Extinction Movement.)


Author: Kathryn McGinley
Last Edited: December 9, 2002

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