Under Construction

Contents: Human Ancestry | Diversity Time scale | Clades

Evolution of Man
In the late 1700's French biologist Jean-Baptiste Lamarck expoused evolution theories based on idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring (also known as heritability of acquired characteristics or soft inheritance).

In 1831, Charles Darwin joined a 5 year survey aboard the HMS Beagle expedition .as a geologist and naturalist. The purpose was hydrographic surveys of the southern part of South America, Galapagos, Tahiti and Australia after having circumnavigated the Earth..
  The Galápagos Islands have the reputation as the place where where Darwin's theory of evolution was born, but Darwin would not realize their significance until two years later.
  During the voyage he found fossils of extinct mammals, and collected and made detailed observations of plants and animals, with results that shook his belief that species were fixed and provided the basis for ideas which came to him when back in England, and led to his theory of evolution by natural selection.
In 1859, he published "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life."
(Here the term "races" is used as an alternative for "varieties" and does not carry the modern connotation of human races.)

From 1856 and 1863 German-speaking Moravian scientist Gregor Johann Mendel conducted experiments with pea plants establishing rules of heredity. He was the founder of the modern science of genetics. See Creation - Evolution - Intelligent Design for the "Creationist" view.

Biologists have long aspired to paint a genetic portrait of the ancestor by running the tree of evolution backward, going from its leaves -- the living creatures of today -- down to the point where all its branches coalesce in a single trunk.
Scientists have been using DNA analysis to help in this excercise, but it has turned out to be more complicated than they thought. (see below)

The rapid (geologically speaking!) diversification of the animals has made it difficult to establish the genealogical relationships between them.

Some reptiles changed so that they could be active even when it was cool. These were the warm blooded cynodonts. They may have had fur to help keep them warm. They could feed at night when other reptiles could not. A new mammal, the primate, appeared about 56 million years ago (mya). The monkeys evolved first and then the apes.

Most ideas and theory on animal evolution are based on:

  • fragmentary fossil record
  • comparative anatomy
  • comparative embryology
  • comparative biochemistry
  • DNA analysis
Animals presumably evolved from unicellular eukaryotes, i.e., protozoa
ARCHAEA [Domain]
Bacteria (single cell, no nucleus) 3bya
Eukaryotes [Domain]
 Protozoa (Cells with a nucleus) 1.2 bya
 Animalia [Kingdom]
 Sponges [Phylum Porifera] (Grouping of cells in an organized colony) 0.8-1bya
    JellyFish (primative nervous system and muscles) 600 mya
     Coral
      Flataworms (Phylum Platyhelminthes)  600-1,000 mya
        (beginnings of a head - mouth and light sensitive spots)
       Brachiopods
       Mollusks [Phylum]
        Nautilus  550 mya
        Trilobites (High-definition eyes)
         Squid
         Echinoderms [Phylum] (star fish) 540 mya
           Lancet Family Alepisauridae (protofish) (Cephalochordata, Amphioxus 440 mya
         Chordata [Phylum] nerve chord.  570 mya
           Urochordata [Class] (Sea Squirts, Tunicates, Ascidians, etc.)
          Vertebrates [Sub-Phylum] 525 mya
            Agnathans are jawless fish. There are two primary marine types of the class Agnatha.
            They are Hagfish and Lampreys. 500 mya 
              Bony Fish - 470 mya
              Fish  400 mya
             Coelacanth (Lungfish) 350 mya
              Tetrapods (terrestrial vertebrates - 4 appendages legs or legs+wings) 350 mya
               Amphibians 
                Synapsida [Class]- (extinct) (looked like reptiles) (300 mya) 
                 Pelycosaurs ("mammal- looked like reptiles") 290 mya
                  Therapsida [Order]- The dominant land animals during the Middle Permian.
                   Cynodonts   222 - 215 mya
                   Early Mammals [Class] (shrew like) 195-164 mya
                    85% genetically similar to humans 
       
Early primates [Order] (lemurs, monkeys, ...) 56 mya (Million years ago)
 
 
Characterized by: Grasping hands, flexible arms, acute 3-D vision, learned behavior, urge for social connections.
93% genetically similar to humans. See DNA below.

Proconsul is an extinct genus of primate without a tail existed from 23 to 17 million years ago in eastern Africa. It is a likely candidate for a common ancestor to apes.

Hominoids [SuperFamily] Apes (Gibbons, ..) 25 mya

Hominidae [Family] Great Apes (Orangutans, ..) 15 mya

Homininae [Sub-Family] (Gorilla, man, chimp) 13 mya [semi-upright posture] 98.4% genetically similar to humans

   A 13 million year old fossil discovered in 2004 in spain, Pierolapithecus catalaunicus,
   is a candidate for a common ancestor between apes and Hominini (chimps and humans).
   See Gorilla walks like a man YouTube
   
Hominini [Tribe (chimp, man) 7 mya
98.8% genetically similar to humans.
The human family is shown here.
Genera - As of 2010 we have identified 6 genera of early man grouped into 4 groups (The earliest Ardipithecus group has 3 genera). The exact links between them has not been established. The only hominin genera existing today are homo (man) and pan (chimps) with 3 species Homo Sapien, Pan troglodytes (chimp), Pan paniscus (bono). The earliest hominin, an ancestor of chimps and humans, probably existed around 7 mya

Below are a some of the 18 hominin species identified from more than 6,000 fossils.
In 2015 a new species, Homo naledi, was discovered in a cave in South Africa.

See the Human Family Tree at The Smithsonian for more.

   Sahelanthropus tchadensis 7 - 6 mya
     Orrorin tugenensis 6.2 - 5.8 mya
     Ardipithecus ramidus 4.4 mya [becoming bipedal]
       (see The Middle Awash project at Berkeley and Discovering Ardi at the discovery channel)
     Australopithecus [Genus] 4 - 2 mya
       Afarensis [Species] 3.9 - 3 mya (Lucy) [mostly bipedal] *
       Africanus 3.3 - 2.1 mya *
     Paranthropus
       Boisei   2.3 - 1.2 mya
       Robustus 1.8 - 1.2 mya
      Homo [Genus] 1-2 mya
        Probably evolved from Australopithecus
        Homo Habilis [Species] 2.4 - 1.4 mya *
        Homo Erectus [Species] 1.9 mya- 143,000 ya 
         Archaic Homo Sapiens The term is typically taken to include several varieties of Homo.
         500,000 - Including:
          Homo heidelbergensis 700,000 - 200,000 ya [large brain] *
           Homo neanderthalensis 200,000 - 28,000 ya
          and Homo rhodesiensis 300,000-125,000 ya
         
           Homo Sapien Sapien (Anatomically Modern Man) 120,000 - 200,000 ya - present 
              Full behavioral modernity - 50,000 ya
       
   * Viable candidate for an ancestor of humans.
 
Classification: Taxonomy & Systematics
Human Family Timeline:

Human Evolution Timeline @ The Smithsonian Institution's Human Origins Program
Human Family Tree at The Smithsonian
Chart of Human Evolution at handprint.
The Evolution of Homo sapiens by John W. Kimball, PhD.

Range of Great Apes 12 million years ago to 5 Million years ago.

An evolutionary explosion between 11 and 9.5 million years ago produced dozens of species of apes. Soon thereafter, the climate of Eurasia began to cool, eventually apes only existed in tropical Africa and the warm forests of east Asia.

Hominini Fossils
Only the oldest or most prominent sites shown.
See Also:
Larger Map and fossil list
Human Fossil Sites at Handprint - Ancestral Lines
Asian Expansion of Homo Erectus
Evolution of Modern Humans: Homo heidelbergensis @ palomar.edu
Evolution of Modern Humans: Early Modern Homo sapiens

 
Migration:
The 1.8 million year old homo erectus fossil in Java and later homo erectus fossils in China indicates there was an early migration.
One theory was that homo sapiens evolved independently there and in Africa. The dominant view among scientists now is the "Out of Africa" or recent African origin hypothesis, which argues that Homo sapiens arose in Africa and migrated out of the continent around 50,000 to 100,000 years ago, replacing populations of Homo erectus in Asia and Homo neanderthalensis in Europe.

There are differing theories on whether there was a single exodus or several. A multiple dispersal model involves the Southern Dispersal theory. In this theory, there was a coastal dispersal of modern humans from the Horn of Africa around 70,000 years ago.
  A second wave of humans dispersed across the Sinai peninsula into Asia, resulting in the bulk of human population for Eurasia.

See Human Migration in History

Common view of human ancestors. This is still theory.

Source: Paleoanthropology - CreationWiki, the encyclopedia of creation science

In 2008 a finger bone was found in the Denisova Cave in southern Siberia. Genetic sequencing suggest that it contributed 4-6% of its genetic material to the genomes of present-day Melanesians (People from Melanesia [New Guinea, ...]). The phalanx was found in a layer, which has been dated to 50,000 to 30,000 years ago. Speculation is it was a branch of Neanderthals which interbred with Homo Sapiens.
See Genetic history of an archaic hominin group from Denisova Cave in Siberia - December 2010, Vol. 468, Nature


Source: Fossil_homs_cranial_capacity_vs_time | NCSE

Is there a missing link? - A "missing link" implies a linear progression from one species to another. But evolution occurs in branching patterns, making a multibranched tree a more appropriate model for understanding evolutionary relationships.
  Fossils representing transitional species are NOT at all rare, especially given the rarity of fossils in general compared with the diversity of life that once existed.
  Humans and chimpanzees have been evolving independently for millions of years. A missing link, a creature halfway between a human and a chimpanzee, is therefore not a useful concept.
  Source: "What does it Mean to be Human", by Rick Potts and Chris Sloan, 2010 National Geographic.

Most of the Homanin fossils have been found in East Africa's Great Rift System (EARS) (A place where tectonic forces are presently trying to create new plates by splitting apart old ones.). However the earliest Homanin, Sahelanthropus tachadensis (Sahel Man from Chad) was found in Chad, north central Africa.
See: Rocking the Cradle of Humanity: New thoughts on climate, tectonics and human evolution, Geotimes, Jan. 2008

See: Hominidae in taxonomy.
Human Migration and History of Man in History
Kimball's A Phylogeny of Living Hominoids
Skeletons in the cupboard - Science - www.theage.com.au

bya - Billion Years ago
mya - Million Years ago

First appearances and relative diversity (width of shaded area) for major groups of animals.

Sponges
Graptolites - Extinct small marine animals
   related to Hemichordata
Cnidarians - jellyfish, coral, sea anemones
Moss Animals - Bryozoa
 look like coral or seaweed
Brachiopods - lamp shells 
  (clam like animals that live in
    extreme cold waters)
Mollusks - oysters, snails, slugs, scallops,
  octopus, squid and clams
Anthropods - Insects - butterflies,
  grasshoppers, beetles, fly, mosquito, moths
Echinoderms - starfish, sea urchins
Chordates - Vertibrates -
   fish, reptiles, birds, amphibians, mammals


The width of the shaded space is an indicator of the number of species.
Source: The Modern View Of Evolution at Estrella Mountain Community College from Life: The Science of Biology, by Purves et al., from Sinauer Associates.

Life evolved very slowely until the cambrian explosion about 530 million years ago.
Gould proposed (in Wonderful Life, 1989) that all modern animal phyla had appeared rather suddenly. But other analyses, argue that complex animals similar to modern types evolved well before the start of the Cambrian.

Origins of Life:
1938 - The Origins of Life

In "The Origins of Life", Russian biochemist, Alexander Oparin, published a theory of how chemical reactions with simple gases such as ammonia (NH3), methane, (CH4), water (H2O), carbon dioxide (CO2) and hydrogen (H2) combined with ultraviolet radiation could have produces other compounds to make amino acids, sugars, phosphates and other building blocks of complex molecules (such as proteins) necessary to living cells.

1953 - Miller-Urey Experiment
While doing graduate work under Harold Urey at the University of Chicago, Stanley Miller conducted the first experimental test of the Oparin model. He sent a high-voltage charge of electricity into the chamber filled with methane (CH4), ammonia (NH3), water vapor (H2O) and hydrogen (H2). After two days Miller found a small (2%) yield of amino acids.
According to Dembski in Mere Creation, there are several problems with this theory based on current knowledge including the lack of nitrogen, the speed with which life emerged and complexity of living cells.

2001 To answer the question of which came first a cell membraned or genetic molecules, Szostak, Bartel and Luisi's paper "Synthesizing Life" (Nature. 2001; 409: 387-390) state that a protocell and genetic molecule had to develop in parallel.

Szostak at Mass. General has shown since how simple fatty acids around in the primative earth could form cell membranes.

2009 - Sutherland article in Nature
John Sutherland, a chemist at the Univ. of Manchester published an article, "RNA world easier to make", Nature, 13 May, 2009, describing his discovery of a route for synthesizing nucleotides from prebiotic chemicals.

See also: Earth History and Extinctions.


Phylogenetic trees:
Cladistic trees, a system based on the a common evolutionary history to group "closely related organisms" has been accepted as the best method available for phylogenetic analysis since the early 2000's.
Archaea was shown to be closer than bacteria to Eukayra (Protista, Animilia, Plante, Fungi) by comparing ribosomal RNA sequences. Carl Woese, 1977
See: Phylogenetic trees
Clades for Humans:
Links to Tree of Life Web (ToL) and Univ. of California Museum of Paleontology (UCMP):
Clade ToL UCMP
Root
Eukaryotes - Multi-celled with nucleus
Animals (Metazoa)
Bilateria - bilaterally symmetrical (front/back, left/right)
Deuterostomia - Develop (embryo) mouth second
Chordata - Hollow nerve cord
Vertebrates - backbone
Terestrial Vertebrates/Tetrapods
Aminiota (mammals, reptiles)
Synapsida - Reptilian like creatures 300 mya
Therapsida - Order under Synapsida
Mammalia
Eutheria - Placental (unborn children carried in the uterus)
Primates
Catarrhini (Humans, great apes, gibbons, Old World monkeys)
Hominidae (great apes)

DNA:
Comparing genomes is difficult. It depends on whether you are comparing nucleotides, chromosomes, genes or something else. For example the chimpanzee has an extra chromosome 24 instead of 23 in humans or a 4% difference. But the human chromosome 2 is a combination of 2 chimp chromosomes with most of the same genes.
You will see some reports that say there is a 4-5% difference between humans and chimps, but the most common number used is 1.2%.

The pufferfish genome, 365 million base-pairs (Mb) in length, has only one-ninth of the DNA of humans, although both vertebrate species have approximately the same number of genes. Why is there so much extra DNA in humans? Much of it appears to be in the form of introns that are substantially bigger than those in pufferfish.

See: Comparing Genomes

Amino Acid Sequence of hemoglobin:
Another way to compare differences in species is to look at the number of amino acids that differ from a human hemoglobin chain with 146 acids.
Gorilla - 1, Rhesus monkey - 8, Mouse - 27, Chicken - 45, Frog - 67.

The longstanding road map for finding the universal ancestor turns out in the light of new data to have given misleading directions, and the road map's chief author, Dr. Carl Woese of the University of Illinois, is proposing a new theory about the earliest life forms.

Scientists have been using DNA analysis to help in this excercise, but it has turned out to be more complicated than they thought. A basic source of the confusion is that in the course of evolution whole suites of genes have apparently been transferred sideways among the major branches. Among animals, genes are passed vertically from parent to child but single-celled creatures tend to engulf each other and occasionally amalgamate into a corporate genetic entity.
See April 14, 1998 NY Times Article "Tree of Life Turns Out to Have Complex Roots"

Full behavioral modernity:
Richard Klein of Stanford thinks that, "What happened 40,000 or 50,000 years ago was the last major change in the genotype. At least the last major biological change. Evolution continues, but the evolution that's involved in making us capable of wielding this vast variety of cultures--that probably stopped around 40,000 or 50,000 years ago and there's been no essential change since."

Klein believes that this change allowed the migration out of Africa.

The social brain hypothesis (2007) was proposed by British anthropologist Robin Dunbar, who argues that human intelligence did not evolve primarily as a means to solve ecological problems, but rather intelligence evolved as a means of surviving and reproducing in large and complex social groups.

See:
Podcast Interview: Richard Klein at the Proceedings of the National Academy of Sciences (PNAS), 2009
Evolution of human intelligence at wikipedia

Books:
Darwin's Ghost : The Origin of Species Updated, 2001, S. Jones
Evolution: The Triumph of an Idea-Carl-Zimmer, 2006
"The Growth of Biological Thought", Ernst Mayr
"Full House", 1996, Steven Gould
"Life Evolving", 2002, Christian de Duve
Life On Earth, 1979, Attenborough A book and TV series from the BBC
The Origins of Life, A. I. Oparin, 1938 (English Translation)

See:
Understanding Evolution at UC Berkeley
Evolution Misconceptions
Classification: Taxonomy & Systematics (History of Classification and evolution)
Human evolution @ Wikipedia
The Tree of Life Web Project (ToL) is a collaborative effort of biologists from around the world. On more than 3000 World Wide Web pages, the project provides information about the diversity of organisms on Earth, their evolutionary history (phylogeny), and characteristics.
Origin And Evolution Of Life at the Encyclopedia of Science
THE EVOLUTION OF LIFE ON THE EARTH Scientific American Article by Steven J. Gould
The Evolution of Mammals
Evolution Library ( Origins of Humankind, ) at pbs.org
Creation - Evolution - Intelligent Design
Tree of Life: Vedrtebrtates at the American Museum of Natural History
Systemataics of Vertebrtes Univ. of California Museum of Paleontology (UCMP)
Evolution | NOVA Labs | PBS
The Invertibrate Animals
Comparing Genomes
Genetic history of an archaic hominin group from Denisova Cave in Siberia - December 2010, Vol. 468, Nature
Evolution Directrory at ActionBioscience.org
http://mcb.harvard.edu/BioLinks/Evolution.html Evolution at Molecular and Cellular Biology Dept at Harvard
Human Evolution M.Tevfik Dorak, B.A. (Hons), M.D., Ph.D.
Nature and Origin of Life on Planetary Bodies
Institute of Human Origins at Arizona State U.

last updated 26 Dec 2014