Homo sapienshuman

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Geographic Range

Humans are currently found throughout the world; in permanent settlements on all continents except Antarctica and on most habitable islands in all of the oceans. All available evidence suggests that humans originated in Africa. (Boaz and Almquist, 2002; Findley, et al., 1975)

Anatomically modern Homo sapiens populations are known from the Middle East as long as 100,000 years ago, from east Asia as long as 67,000 years ago, and southern Australia as long as 60,000 years ago. European Homo sapiens fossils are known from 35,000 years ago. Homo sapiens populations were once thought to have colonized the New World approximately 11 to 13,000 years ago, but recent research indicates earlier dates of colonization. This is an area of active research. (Boaz and Almquist, 2002)

Habitat

Humans are found in all terrestrial habitats worldwide. Humans extensively modify habitats as well, creating areas that are habitable by a much reduced set of other organisms, as in urban and agricultural areas. With the aid of technologies such as boats, humans also venture into many aquatic habitats, primarily to obtain food. (Boaz and Almquist, 2002; Findley, et al., 1975)

Physical Description

Humans are an exceptionally diverse species morphologically and many aspects of size vary substantially with environmental factors such as nutritional status. Historically there has been an effort to organize human physical variation into "races," although there is no scientific basis for the application of a race concept to human variation. Human physical variation is continuous and available evidence suggests that gene flow among human populations throughout their history has been the rule rather than the exception. (Boaz and Almquist, 2002)

Humans are characterized by their bipedalism and their lack of significant body hair. Males are generally larger than females, with more pronounced muscle development and generally more hair on the face and torso than females. (Boaz and Almquist, 2002)

  • Sexual Dimorphism
  • male larger
  • sexes shaped differently

Reproduction

Human cultures are marked by a wide range of approaches to mating. Child-rearing in most cultures is accomplished with some degree of help and cooperation from other members of the group, including related and unrelated members. (Boaz and Almquist, 2002)

Humans are capable of breeding throughout the year. Gestation length is 40 weeks on average, a fairly long gestation length for a primate species with altricial young. Typically one young is born, although twins occur occasionally and multiple births rarely. Interbirth intervals, birth weights, time to weaning, independence, and sexual maturity all vary substantially with nutritional status of mothers and young and are influenced by cultural practices. (Boaz and Almquist, 2002; Martin and MacLarnon, 1990)

  • Breeding interval
    Human females can reproduce up to once every 10 months, although typical birth intervals are longer and vary substantially.
  • Breeding season
    Humans can breed at any time of the year.
  • Range number of offspring
    1 (low)
  • Average gestation period
    40 weeks

Human infants are born in an altricial state and require intense and long-term care to ensure survival. Parental care is variable across human cultures, but generally the mother plays a large role in caring for infants through weaning. Family members and unrelated community members also often play large roles in caring for young. Human young experience an extended period of adolescence in which many essential skills and cultural knowledge are learned and practiced. Human social structures are complex and frequently young remain part of the same larger social groups as their parents and their paternal and maternal families. Social stature of parents often also plays a large role in the social stature of the young. (Boaz and Almquist, 2002; Martin and MacLarnon, 1990)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • post-independence association with parents
  • extended period of juvenile learning
  • inherits maternal/paternal territory
  • maternal position in the dominance hierarchy affects status of young

Lifespan/Longevity

Human lifespans vary tremendously with nutritional status and exposure to diseases and trauma. Humans can live more than 100 years; the longest lived human that has been documented was 122 years old. Most humans live 50 to 80 years old, providing they survive their most vulnerable childhood years. Average life expectancy in many parts of the developing world is from less than 40 years old to 65 years old. In the developed world average life expectancy can be over 80 years old. (U.S. Central Intelligence Agency, 2008)

  • Typical lifespan
    Status: wild
    32 to 84 years

Behavior

Humans are one of the most behaviorally, socially, and culturally complex animal species. Ancient humans were nomadic hunter gatherers but the development of agriculture approximately 10,000 years ago revolutionized the way that humans live. Agriculture ultimately led to increases in regional human populations and concentration in urban centers, and dramatically altered the cultures, economies, and relationships among human populations. In general, humans are highly social animals that are active mainly during the day. Some human populations remain nomadic or migratory, while most live mainly in one general area. (Boaz and Almquist, 2002; Findley, et al., 1975)

One of the most notable aspects of human biology and evolution is the extensive use of tools. Early human populations constructed sets of specialized tools, such as chisels and knife blades, from stones, bone, antler, and ivory. Human technological innovation is one of the most definitive human characteristics. Related to this innovation is the complex development of human art and symbolism, including written languages. (Boaz and Almquist, 2002)

Home Range

Human home ranges vary widely among populations and use of space is extremely flexible.

Communication and Perception

Like most primates, humans use vision extensively in perception and communication. Humans have excellent color vision, although visual acuity in low light is limited. Humans also use sounds extensively. Human languages represent one of the most complex systems of communication in the animal world, and the diversity of human languages is astounding. Touch is an important mode of perception, it is especially important in close social bonds. Humans have a moderately well developed sense of smell and taste, which is used to determine the suitability of foods and discover information about the environment and conspecifics. (Boaz and Almquist, 2002)

The evolution of complex language is considered one of the hallmarks of Homo sapiens. Archaic humans were capable of complex language, although Homo sapiens anatomy seems to have evolved to favor the production of complex sounds in anatomically modern humans. (Boaz and Almquist, 2002)

Food Habits

Humans generally eat a highly variable omnivorous diet. The components of diets vary tremendously with regional availability of foods. Some human cultures restrict their diet to a vegetarian one, relying on plant sources of proteins. Foods are often extensively prepared and stored for future use. The use of fungal colonies, such as yeasts, for creating cultured foods, such as beer, bread, and cheeses, is widespread. (Boaz and Almquist, 2002)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • fish
  • eggs
  • blood
  • body fluids
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • aquatic crustaceans
  • echinoderms
  • other marine invertebrates
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit
  • nectar
  • pollen
  • flowers
  • sap or other plant fluids
  • algae
  • macroalgae
  • Other Foods
  • fungus
  • microbes

Predation

Humans have few natural predators and often sit at or near the top of the food chain in regional ecosystems. Humans are sometimes opportunistically preyed on by large wild cats, such as tigers (Panthera tigris) and lions (Panthera leo). Other instances of large, carnivorous animals eating humans are often cases of mistaken identity or are opportunistic events. This includes cases involving large sharks, bears, monitor lizards, and crocodiles.

Ecosystem Roles

Humans act as top predators in many ecosystems, although they are also sometimes preyed on by larger predators, such as tigers. Humans modify habitats and ecological communities in countless ways, often substantially changing the interactions of nearly all other species in those habitats. (Boaz and Almquist, 2002)

Humans are parasitized by many species of internal and external parasites. Some research suggests that hairlessness in humans is an adaptation to reduce ectoparasite loads. (Boaz and Almquist, 2002)

Humans and human societies have evolved multiple relationships with other species, including commensal species and domesticated and companion species. Human commensals are too numerous to mention, but some important commensal species are house mice (Mus musculus), black rats (Rattus rattus), Norway rats (Rattus norvegicus), and Oriental cockroaches (Blatta orientalis). Important domestic species include domestic dogs (Canis lupus familiaris), pigs (Sus scrofa), cattle (Bos taurus), sheep (Ovis aries), goats (Capra hircus), chickens (Gallus gallus), guinea pigs (Cavia porcellus), horses (Equus caballus), llamas (Lama glama), camels (Camelus species), turkeys (Meleagris gallopavo), honeybees (Apis mellifera), and many other animals. Humans have also domesticated many species of plants for food and other uses, such as corn (Zea mays), rice (Oryza sativa), wheat (Triticum aestivum), manioc (Manihot esculenta), apples (Malus domestica), and soy (Glycine max). (Boaz and Almquist, 2002)

  • Ecosystem Impact
  • creates habitat
Mutualist Species
Commensal/Parasitic Species

Economic Importance for Humans: Negative

Human interactions are often complex and negative at interpersonal levels and among social groups, cultures, and governments. Human activities often destroy or transform ecosystems, and these changes can have negative economic and/or medical impacts on other human populations. (Boaz and Almquist, 2002)

Conservation Status

Human populations are not monitored by conservation agencies. Although human populations worldwide are large and growing, some regional or isolated populations may be in decline as a result of economic disadvantage, disease, habitat degradation, emigration, and cultural erosion.

Other Comments

Earliest Homo sapiens appeared approximately 700,000 years ago, although anatomically modern humans are known from about 100,000 years ago. Patterns of colonization of the world by ancient humans and the details of interactions between ancient Homo sapiens and co-occurring Homo species are areas of active research. (Boaz and Almquist, 2002)

Contributors

Tanya Dewey (author), Animal Diversity Web.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carrion

flesh of dead animals.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cooperative breeder

helpers provide assistance in raising young that are not their own

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

intertidal or littoral

the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

macroalgae

seaweed. Algae that are large and photosynthetic.

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

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pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polygynous

having more than one female as a mate at one time

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Boaz, N., A. Almquist. 2002. Biological Anthropology: A Synthetic Approach to Human Evolution. New Jersey: Prentice Hall. Accessed December 03, 2007 at http://wps.prenhall.com/hss_boaz_biological_2/.

Findley, J., A. Harris, D. Wilson, C. Jones. 1975. Mammals of New Mexico. Albuquerque: University of New Mexico Press.

Martin, R., A. MacLarnon. 1990. Reproductive patterns in primates and other mammals: the dichotomy between altricial and precocial offspring. Pp. 47-80 in C DeRousseau, ed. Primate Life History and Evolution. New York: John Wiley and Sons, Inc..

Ruvolo, M. 1997. Molecular Phylogeny of the Hominoids: inferences from multiple independent DNA sequence data sets. Molecular Biology and Evolution, 14: 248-265.

U.S. Central Intelligence Agency, 2008. "Rank order life expectancy" (On-line). CIA Factbook. Accessed May 06, 2008 at https://www.cia.gov/library/publications/the-world-factbook/rankorder/2102rank.html.