New species develop from existing species {species evolution} {evolution, species}|.
cells
On early Earth, heat, light, lightning, and meteor collisions formed carbon-containing molecules {organic molecule, life} with attached hydrogen, oxygen, nitrogen, sulfur, and phosphorus atoms. Simple organic molecules combined to make sugars, amino acids, nucleotides, and fatty acids, which combined to make carbohydrates, proteins, nucleic acids, and lipids. Large molecules can have shapes and structures and can have multiple binding and reaction sites. Structural molecules combined to form cells, viruses, and bacteriophages.
species
The first cells were the first species. Cells evolved into single-cell Archaea. Archaea evolved into bacteria and single-cell plants and animals. Single-cell organisms evolved into multicellular plants and animals. Multicellular animals evolved into invertebrates. One invertebrate species evolved into vertebrates. One vertebrate species evolved into fish. One fish species evolved into amphibians. One amphibian species evolved into reptiles. One reptile species evolved into mammals. One mammal species evolved into primates. One primate species evolved into monkeys. One monkey species evolved into apes. One ape species evolved into anthropoid apes (great apes) (hominids). One hominid species evolved into hominins (human ancestors) and Homo sapiens.
features
Prokaryotes have no nucleus. Eukaryotes have nuclei. Multicellular eukaryotes have neurons, sense cells, and muscle cells. Invertebrates can have bilateral symmetry, as in flatworms. Prechordates have notochord beginnings. Chordates have notochord in one development stage. Vertebrates have vertebrae. First fish have cartilage. Bony fish have bones. Lobe-finned fish have fin stumps. Fresh-water lobe-finned fish live in fresh water. Amphibians live on land and in water. Reptiles can live only on land. Mammals make milk. Primates have forward eyes. Old World monkeys have tricolor vision. Hominids, hominins, Homo, Homo habilis, Homo erectus, and Homo sapiens follow.
requirements
Evolution requires objects that carry coded information about how to build and maintain structures and functions and about how to replicate themselves. Evolution requires mechanisms to build objects, maintain objects, replicate objects faithfully, and provide slight variations in coded information. Evolution requires environment that has scarce resources. Evolution requires competition among similar objects. Objects then replicate more or better.
levels
Evolution can affect whole Earth, biomes, ecosystems, clades, or demes. Evolution can act on kingdoms, phyla, classes, orders, families, genuses, species, and varieties. Evolution can act on organs, tissues, cell lines, chromosomes, genes, exons, DNA functional regions, and nucleotides. Different levels can have different selection laws.
environment
If organisms change, other organisms change in response, and relations between other organisms and environment change. Change can cause exponential change. However, change is disruptive and decreases survival for most organisms.
Universal Darwinism
Systems that make copies, have variations, and have a selection mechanism can evolve {Universal Darwinism} [Dawkins, 1976] [Dawkins, 1986] [Dawkins, 1995].
intelligent design
Religionists can believe that God helped form some species. God used special structures and functions that distinguish humans from other species. However, intelligent design does not seem to allow human-appendix creation or maintenance. Complex life forms need to eat less complex forms. Intelligent design allows arbitrary changes and so has no testable hypotheses.
criticisms
Perhaps, both intelligent design and evolution are incorrect. Really, physical laws determine all, with no higher principles. Evolution works only haphazardly, with most species dying out.
Biological Sciences>Biology>Evolution
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Date Modified: 2022.0224