Earth has 2,500,000 species in many categories {classification, biology}. Earliest life was one-celled organisms. Archaea included thermophiles. Bacteria included proteobacteria and later cyanobacteria blue-green algae. Eukaryota included metamonad, parabasalid, trypanosoma, ciliates, and flagellates. Multicellular organisms arose from eukaryotes.
Many-celled organisms {metazoa}| {multicellular organism} include fungi, plants, and animals. Metazoa have specialized tissues.
evolution
Only eukaryotes can be multicellular organisms. About 650 million years ago, protozoa clustered, and cells differentiated into different tissues. Later eukaryotes evolved neurons. Later, jellyfish evolved sodium-ion channels for action potentials, which allow neurons to communicate over any distance.
gene transfer
Early eukaryotes incorporated early alpha-proteobacteria to make mitochondria. Early eukaryotes incorporated early cyanobacteria to make chloroplasts. Perhaps, eukaryote cytoskeleton and internal membranes came from early spirochetes, flagellates, or ciliates.
Organism names are genus name followed by species name {binomial system} {binomial nomenclature}|, such as Escherischia coli.
One-celled organisms {prokaryote}| {Monera} {Prokaryota} can have no distinct nucleus or other cell organelles. Prokaryotes include archaebacteria and eubacteria. Eubacteria include blue-green-algae cyanobacteria.
Cells {eukaryote}| (Eukaryota) (Eukarya) can have one cell nucleus surrounded by membrane. Eukaryotes include protozoa, fungi, plants, and animals. Eukaryotes are not Archaea, bacteria, blue-green algae, viruses, or bacteriophages.
The largest organism groups {kingdom, classification}| include non-nucleated single-cell archaebacteria (Archaea), non-nucleated single-cell eubacteria (Bacteria), nucleated single-cell protozoa (Protista) {protist}, nucleated fungi (Fungi), nucleated multi-cell plants (Plantae), and nucleated multi-cell animals (Animalia).
domains
Domains are Archaea, Bacteria, and Eukaryota. Archaea include thermophiles. Bacteria include proteobacteria, cyanobacteria, and other bacteria. Eukaryota include protozoa, yeast and other fungi, algae and other plants, and animals.
algae
Bacteria include cyanobacteria blue-green algae. Other algae are plants.
yeast
Fungi include yeast.
Kingdoms have major organism types {phylum} {phyla} {division, classification}|.
Divisions/phyla have subdivisions {class, classification}|.
Classes have subclasses {order, classification}|.
Orders have suborders {family, classification}|.
Families have subfamilies {genus, classification}|.
Genuses have interbreeding subgenuses {species, classification}|.
Species have subspecies {variety}|.
Humans have varieties {race, people}, such as north European white {Caucasian, people}, south European white {Mediterranean, people}, European and American Indian {mestizo}, Spanish-speaking or Portuguese-speaking country of South and Central America {Hispanic}, Central America {Latino}, Mexico {Chicano}, Africa {Negro} {black, person} {African-American}, and Asia {Asian} {Oriental, people} {Asian-American}.
types
People have three races, totaling 30 varieties.
Races {Caucasoid race} can include the varieties Mediterranean, Nordic, Alpine, Armenoid, and Dinaric. It can have more pale red, white, or light brown skin color, be taller, have longer or broader head, have light to dark hair, and have higher nosebridge. Armenoid has Caucasian and Mongoloid. Dinaric has Caucasian, Negroid, and Mongoloid.
Races {Negroid race} can include the varieties African, South Pacific, Melanesian, Oceania, White Hottentots, Bushmen, extinct Tasmanian, and Negritos or pygmies. It can have browner skin color, longer head, thicker lips, darker and coarser hair, darker eyes, lower nosebridge, and broader nostrils.
Races {Asiao-American Race} {Yellow Race} {Mongoloid race} can include the varieties Tungus in Siberia, Oriental, Eskimo, Indonesian, American Indian, Ainu in Japan, Australoid, and Veddoid, as well as Beijing Man, Lantian Man, and Jinniushan Man. Oriental has Chinese and Japanese. Oceanian has New Guinean, Australian, and Aborigine. Eskimos are more separate from Oriental than Oceanian. Mongoloid race started in Central and East Asia and went to South Asia and Southeast Asia. It can have more yellow or red skin color, be average height, have broader head, have less body hair, have darker eyes, have more epicanthic fold, have lower nosebridge, have higher eye sockets, have flat face bones, have higher superciliary arches, have more spade-shaped incisor insides, and have darker, straighter, and coarser hair.
Aborigines in Australia, Dravidians in south India, Polynesians in South Pacific Ocean, and Ainu in north Japan are hard to classify.
dispersion
Gene differences show that original Homo sapiens split into proto-Africans-and-Europeans, proto-Oceania, proto-American Indians, and proto-Oriental peoples. Then African Negritos and Bushmen separated from European Germanic and Mediterranean, so Europeans were intermediate between proto-African and proto-Oriental peoples.
Alu-repeat and short-tandem-repeat polymorphisms divide people into sub-Saharan Africa, Europe and West Asia, East Asia, Polynesia, and Americas groups. Perhaps, sub-Saharan Africa had two groups, including Mbuti pygmies. Genetic variants are 90% same, so group differences are maximum 10%.
cold adaptations
In cold regions, people tend to have shorter limbs, larger bodies, thicker eyelids, flatter noses, flatter foreheads, and broader cheeks.
factors
Decreased environmental pressures, increased mutation-causing agents, more socially-useful genes, greater specialization, and faster environment changes affect human evolution.
Y-chromosome studies indicate that modern human did not arise from multiple origins {multiregional hypothesis}.
Y-chromosome studies indicate that modern human races arose from African population [-89000 to -35000] {out-of-Africa hypothesis}.
Organism-classification systems {cladistics}| can depend on evolutionary, gene, structural, and functional features.
Species can split into independently evolving lines {clade}|. Different clades have different speciation rates, which can change over time. Clades determine classes and hierarchies, shown in branching diagrams {cladogram}. Cladogram nodes represent shared homologies.
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Date Modified: 2022.0225