• BASIC IDEAS.  Evolution is the scientific concept that all living creatures descended with modification
  from earlier life forms through natural processes over several billion years. 
  • Introduction  for Biology 103
  • Natural Selection for Biology 103
  • Speciation (how species form) for Biology 103
  • Fossils, Genes, and Phylogenies for Biology 103
  • What is a scientific theory?
  • Links to basic information about evolution
  • The Tree of Life http://www.sciencemag.org/feature/data/tol/ & http://phylogeny.arizona.edu/tree/phylogeny.html
• Professional Resources
• Creationism  
• Darwin  
• Fossils
• Molecular Analysis of Evolution 
• Plant Evolution Details
• Sexual Selection
• Evolution in the News 
• A quiz:  http://whyfiles.org/095evolution/quiz.html 
• a "lab":  Natural Selection Among Playing Cards http://www.indiana.edu/~ensiweb/lessons/ns.cum.l.html 
• Human Evolution  
  • video + http://www.becominghuman.org
  • Toumai skull plus other milestones in human origins and evolution (free access) http://www.nature.com/nature/ancestor/
  • Human Origins articles from Science Magazine (2002)

    • Differences between humans and chimps http://www.sciencemag.org/cgi/content/full/296/5566/233 

    • In Search of the First Hominids http://www.sciencemag.org/cgi/content/full/295/5558/1214

    • What made humans modern? http://www.sciencemag.org/cgi/content/full/295/5558/1219 
    • Tracing Human Populations with Genetics http://www.sciencemag.org/cgi/content/short/298/5602/2381
      Perspective http://www.sciencemag.org/cgi/content/short/298/5602/2342
  • Human Evolution Issue of Science Magazine (2001) http://www.sciencemag.org/content/vol291/issue5509/index.shtml 
    • introduction to this issue http://www.sciencemag.org/cgi/content/summary/291/5509/1721 
    • genetic clues about human migration http://www.sciencemag.org/cgi/content/full/291/5509/1742 
    • more http://www.sciencemag.org/cgi/content/summary/291/5509/1721#related

  • new (2003) clues about human evolution and ancient civilizations. http://www.sciencemag.org/cgi/content/short/300/5619/607 http://www.sciencemag.org/cgi/content/short/300/5619/562  http://www.sciencemag.org/cgi/content/abstract/1084114 http://www.sciencemag.org/cgi/content/short/300/5618/407a http://www.sciencemag.org/cgi/content/short/300/5617/315
    http://www.sciencemag.org/cgi/content/short/300/5617/229a 

  • new (2003) ideas about hominid relatives http://www.sciencemag.org/cgi/content/full/299/5615/1994
  • evolution of skin color http://www.pubmedcentral.com/articlerender.fcgi?artid=212702 
  • Is your date a descendent of Genghis Khan? http://www.nytimes.com/2003/02/11/science/11KHAN.html
  • Genomic Views of Human History. pp. 451-453 in the 1999 Genome Issue:  http://www.sciencemag.org/cgi/content/full/286/5439/446
  • Early humans http://anthro.palomar.edu/homo2/default.htm 
  • DNA Studies Challenge the Meaning of Race (in the 1998 Genome issue) http://www.sciencemag.org/cgi/content/full/282/5389/654 (see also Ethics Lab)
  •  Longer discussion of the genetics of human "races":  http://www.theatlantic.com/issues/2001/04/olson-p1.htm 
• Molecular Analysis of Evolution 
  • mitochondrial DNA http://www.geneticorigins.org/geneticorigins/mito/intro.html 
  • ALU http://www.geneticorigins.org/geneticorigins/pv92/intro.html 

  • gene duplications, speciation, and disorders http://www.sciencemag.org/cgi/content/short/297/5583/1003  gene duplications in the human genome that most likely arose about 40 million years ago, and that have been linked to a number of genetic disorders. Using a new statistical approach, the team compared sequences of the two publicly available versions of the genome, and identified 169 "hot spots" of DNA duplication -- 24 of which have been associated with genetic disease. An accompanying Perspective by M. Lynch ( http://www.sciencemag.org/cgi/content/short/297/5583/945  ) discussed how DNA duplication could contribute to speciation, and commented on other recent data on fine-scale changes in chromosomal integrity.

  • playing with phylogenies:   http://aleph0.clarku.edu/~djoyce/java/Phyltree/cover.html (new)

  • The latest research on evolution with DNA evidence:

    • DNA origins/phylogeny: http://www.nytimes.com/library/national/science/061300sci-life-origins.html
    • 1999 Evolution Issue of Science [accessible by subscription or at library terminals only]:  
      • Studying evolution in the laboratory:  http://www.sciencemag.org/cgi/content/full/284/5423/2108
      • Why did nature choose RNA as the first genes?  http://www.sciencemag.org/cgi/content/full/284/5423/2118
      • "The history of evolution and biodiversity is fundamentally a history of the evolution of species interactions." "Most living organisms have evolved in ways that absolutely require them to use a combination of their own genetic machinery and that of one or more other species if they are to survive and reproduce."   "Even now, among human populations one-third of deaths are caused by infectious disease."  "As we continue to manipulate biodiversity, our experience so far with the evolution of virulence in diseases, short-term effectiveness of resistant crop varieties, and rapid evolution of interactions within natural communities suggests that the health and welfare of human societies will demand an increased understanding of the ongoing evolutionary dynamics of species interactions." excerpts from http://www.sciencemag.org/cgi/content/full/284/5423/2116
      • and other interesting articles from this and other issues of Science.
    • The latest news on evolution of human sex chromosomes: 
      • tracing the origins of ethnic groups http://www.nytimes.com/2001/04/10/health/10GENE.html 
      • human sperm evolves faster than other human DNA, supporting hypotheses about ancestral mating habits: http://www.nytimes.com/library/national/science/health/012100hth-sex-sperm.html
    • Hemoglobin evolution: http://www.nytimes.com/library/national/science/100599sci-hemoglobin.html
    • transposons in human evolution: http://helix.nature.com/nsu/991007/991007-8.html
    • Which of our genes makes us human?  http://www.sciencemag.org/cgi/content/full/281/5382/1432
• Professional-Level Articles

• Resources for learning more
  • AAAS (American Association for the Advancement of Science) Evolution Resources http://www.aaas.org/spp/dser/evolution/  
  • Science Magazine:  the 25 June 1999 issue featuring Evolution
  • a short textbook on evolution: http://www.talkorigins.org/faqs/faq-intro-to-biology.html (see links at end)
  • an entire course on evolution with summaries of main points and great links: http://nsm1.nsm.iup.edu/rgendron/EvolutionOnTheWeb.shtml
  • A site specializing in scientific responses to creationism:  http://www.talkorigins.org/
  • Darwin's most important book (complete text): http://www.literature.org/Works/Charles-Darwin/origin/
  •  http://www.nceas.ucsb.edu/~alroy/lefa/lophodon.html
  • eight different evolutionary "episodes" that include video clips, biographies, and research of leading scientists, plus featured animal pages with facts, photos, and links to related Web sites.http://www.pbs.org/kcet/shapeoflife/
  • Alfred R. Wallace (who independently developed the theory of Evolution by Natural Selection) http://www.wku.edu/~smithch/index1.htm
  •   A site specializing in scientific responses to creationism:  http://www.talkorigins.org/
  • Speciation summary: http://www.cc.ndsu.nodak.edu/instruct/mcclean/plsc431/popgen/popgen6.htm
  • Models of Speciation, Genetics of Speciation, and Cases of Speciation are three lectures recommended from a course at Brown University:  http://biomed.brown.edu/Courses/BIO48/lectures
  • Darwin's most important book (complete text): http://www.literature.org/Works/Charles-Darwin/origin/
  • Darwin
  • Creationism
  • More about human evolution http://www.becominghuman.org/ 
  • Top 10 Darwin web sites: http://news.bmn.com/hmsbeagle/47/recroom/topten.htm
  • Top 10 Theories of Dinosaur Extinction:  http://news.bmn.com/hmsbeagle/52/recroom/topten.htm
  • History of Palaeozoic Forests: http://www.uni-muenster.de/GeoPalaeontologie/Palaeo/Palbot/ebot.html
  • Coelacanth: The Fish Out of Time: http://www.dinofish.com/ 
  • early history of atmosphere ENHANCED: http://www.sciencemag.org/cgi/content/full/288/5466/626
  • latest (2002) on the Big Bang origin of the universe http://www.nytimes.com/2002/09/20/science/20COSM.html  
    & http://www.csmonitor.com/2002/1003/p25s01-stss.html 
  • the anti-matter research http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v419/n6906/full/419439a_fs.html 
  • origins of life and the classic Miller&Urey experiment; RNA evolution http://www.dnaftb.org/dnaftb/26/concept/ 
  • mitochondrial DNA http://www.dnaftb.org/dnaftb/30/concept/index.html 
  • genetic homologies http://www.dnaftb.org/dnaftb/40/concept/index.html 
  • Tree Rings  
  • Enhanced: How Old Is the Flower and the Fly? (advanced article from SCIENCE magazine; use library terminals
  • Just in time for Halloween:  comparative anatomy (with some homologies) of bones: http://www.eSkeletons.org/ 
  • phylogeny for a polio outbreak http://www.sciencemag.org/cgi/content/full/296/5566/356/F3

• FOSSILS
  • RADIOCARBON dating.    Basics and more.
  • Fossil study: www.ucmp.berkeley.edu/Paleonet  
  • an e-periodical for fossil study  http://palaeo-electronica.org/toc.htm 
  • Fossil record debate from NATURE: begin at first and last entries. 
      http://helix.nature.com/debates/fossil/
  • how they tell from isotopes and other evidence what archaeological specimens ate. (also explains c3/c4 ratios) http://www.sciencemag.org/cgi/content/full/283/5400/335 (Use library terminals)
  • More links on isotopes:  http://www.sciencemag.org/cgi/content/full/282/5395/1840
  • 3D gallery of modern and fossil primate relatives and ancestors
    http://www.anth.ucsb.edu/projects/human/
  • Geological Periods, etc.
  •  

• Special Fossil Collection from the Scout Report 

  • 1. "The Oldest Fish in the World" http://www.admin.cam.ac.uk/news/pr/1999110401.html
  • 2. "Field Museum Scientists Discover what appear to be World's Oldest Dinosaur Fossils" http://www.fmnh.org/research_collections/geology/flynn.htm
  • 6. Department of Paleobiology http://www.nmnh.si.edu/paleo/
  • 8. Early Dinosaur Studies in North America
      http://www.ucmp.berkeley.edu/diapsids/dinodiscoveriesna.html
  • 10. Paleontological Resources: Links http://www.nmnh.si.edu/paleo/links.html

  These numbered links above are from The Scout Report for Science & Engineering, Copyright Internet Scout Project 1994-2000. http://scout.cs.wisc.edu/

   

   

  News Stories

  • Adaptive mutation is common in E. coli,   genetic mutation rates in bacteria happen more when the microorganisms find themselves in strange and stressful circumstances and also...

  • New genomic data helps resolve biology's tree of life  A team of scientists from the Howard Hughes Medical Institute at the University of Wisconsin-Madison, writing in the current issue (Oct. 23. 2003) of the prestigious journal Nature, show that using base sequences from a hundred genes, instead of one or two, allows a computer to build a phylogeny without errors.

  • evolution and cancer are 'fragile' regions exist in the human genome more susceptible to gene rearrangements?

  • unexpected rapid evolution in Caribbean lizards Biologists have documented unprecedented levels of speciation and diversification

  • Natural selection's fingerprint identified on fruit fly evolution gene prevents hybridization of new species?

  • University of Georgia scientists plot key events in plants' evolution:  it's gene duplication

  • Mouse study suggests mammoth evolutionary change fast and maybe caused by human settlers

  •  how complex functions can evolve computer simulations of natural selection work convincingly

  • New thoughts on evolution arise when sex life of beer yeast starts biologists fermenting new ideas  

  • Darwinian evolution at its simplest:  did life originate with RNA-enzymes with only 2 bases?

  • Iron-reducing microbes:  the producers >3 billion years ago?  http://www.nytimes.com/2003/09/09/science/09VENT.html or http://www.sciencemag.org/cgi/content/full/301/5635/934

  • Hummingbirds Fit Their Flowers (adapted from Science Roundup)  Following in Darwin's footsteps, a report in the 25 Apr 2003 *Science* ( http://www.sciencemag.org/cgi/content/short/300/5619/630 ) presented a coevolutionary tale of hummingbirds and their flowering food plants set in the islands of St. Lucia and Dominica in the Lesser Antilles. Hummingbirds show wide variations in body mass, color, and size and shape of their bills and wings. These differences are especially pronounced between males and females -- a characteristic known as sexual dimorphism -- and are exemplified in the purple-throated carib hummingbird, a species in which the larger males have a short, straight bill and the smaller females have a long, curved one. Males of this species tend to favor nectar from *Heliconia caribaea*, whose short, straight flowers match the shape of their bill; females prefer the longer, more curved flowers of the related species *H. bihai*. On St. Lucia, *H. bihai* has compensated for the rarity of *H. caribaea* by evolving a second color morph with straighter flowers that better fit the male bill. On Dominica, this remarkable pattern of coadaptation is reversed:
    *H. caribaea* has evolved a second color morph with flowers that match female bills. These findings strongly suggest that bill dimorphism is driven by ecological pressures. 
    Perspective : http://www.sciencemag.org/cgi/content/short/300/5619/588 .

  • Healthy Males Flaunt It?  (adapted from Science Roundup)  Females pay attention -- especially when it comes to choosing a mate. In the animal kingdom, males unabashedly use bright colors to attract females, and nowhere is this more apparent than among birds. Still, evolutionary biologists have struggled to explain why a male's showiness makes him more desirable. In the 4 Apr 2003 *Science*, two research teams demonstrated that in some birds, a female's attraction to a brighter beak may actually ensure her a healthy mate.  http://www.sciencemag.org/cgi/content/short/300/5616/103 ) 
    ( http://www.sciencemag.org/cgi/content/short/300/5616/125 ) 
    News story :( http://www.sciencemag.org/cgi/content/short/300/5616/29 ), the implication of these reports is that when females opt for flashy males, they are actually choosing mates with robust immune systems -- and, thus, greater fitness levels than the more drab competition. So for some creatures, maybe looks *are* everything . . .

  • new clues about human evolution and ancient civilizations. http://www.sciencemag.org/cgi/content/short/300/5619/607 http://www.sciencemag.org/cgi/content/short/300/5619/562  http://www.sciencemag.org/cgi/content/abstract/1084114 http://www.sciencemag.org/cgi/content/short/300/5618/407a http://www.sciencemag.org/cgi/content/short/300/5617/315
    http://www.sciencemag.org/cgi/content/short/300/5617/229a 

  • phylogenetic forensic evidence in murder-by-HIV case http://www.biomedcentral.com/news/20021015/02/ 

  • CT scans to "see" inside Doushantuo fossil embryos http://www.eurekalert.org/pub_releases/2002-10/gsoa-ife102502.php 

  • Was the Cambrian explosion caused by environmental perturbations by the first of the new animals? http://www.eurekalert.org/pub_releases/2002-10/gsoa-sba102502.php 

  • Humans and Chimp DNA comparisons (new 25 Oct 2002) http://www.sciencemag.org/cgi/content/full/298/5594/719b 

  • chickens tainted with antibiotic-resistant bacteria:  http://www.boston.com/dailyglobe2/345/nation/Half_of_store_chickens_found_tainted+.shtml 

  • Is West Nile Virus evolving? http://www.nature.com/nsu/021014/021014-5.html 

  • The language gene:  http://www.nature.com/nsu/020812/020812-6.html 

  • sexy chemicals drive speciation?  http://www.eurekalert.org/pub_releases/2002-09/cuns-slt091002.php 

  • lateral transfer may destroy evidence of genetic homologies http://www.eurekalert.org/pub_releases/2002-06/uoia-nce061402.php 

  • Neanderthal baby found http://www.nature.com/nsu/020902/020902-6.html 

  • a big-leap dominant mutation refutes creationist argument http://www.eurekalert.org/pub_releases/2002-02/uoc--fge020402.php 

  • different photosynthetic pathways suggest importance of gene duplication http://www.eurekalert.org/pub_releases/2002-07/tifg-ctt062802.php 

  • experimental sympatric speciation http://www.eurekalert.org/pub_releases/2002-09/uor-bne092502.php 

  • the latest (26 April 2002) on Darwin's finches 
    http://www.sciencemag.org/cgi/content/full/296/5568/633 

  • selection for stable base pairs in the first DNA?  http://www.nature.com/nsu/020916/020916-4.html 

  • The activation of a single gene, called *foraging* (or *for*) causes the transition of female honeybees from "stay at home" hive workers to foragers that strike out from the nest to collect nectar and pollen. Remarkably, the *for* gene is the same one that, in the much less regimented lifestyle of fruit fly populations, controls whether a fly is a "sitter" that seeks food over a limited area, or a "rover" that collects food over a broader zone.  http://www.sciencemag.org/cgi/content/full/296/5568/636 

  • whales came from hippos?  http://www.nytimes.com/2001/10/02/science/life/02WHAL.html 
  • populations living around natural radiation evolve faster?  http://news.bmn.com/news/story?day=021001&story=2 
  • How Bugs Resist Pesticides.  Just as prolonged use of antibiotics has led to the evolution of countless strains of resistant microbes, the introduction of new pesticides is causing a global spread of resistance among insects. To better understand the mechanisms driving this threat, Daborn et al. ( http://www.sciencemag.org/cgi/content/short/297/5590/2253 ) examined the genetic basis for DDT resistance in fruit flies, and reported their results in the 27 Sep 2002 *Science*. Using microarray analysis, they found that in 20 globally distributed and resistant strains, resistance was made possible by the overexpression of a single copy of the *Cyp6g1* gene for a cytochrome P450 -- one of a family of metabolic enzymes that, in insects, is responsible for key functions including toxin breakdown. Surprisingly, *Cyp6g1* confers resistance not only to DDT, but to a broad range of insecticide groups -- which greatly increases the risk of resistance extending to new chemical agents. As noted in an accompanying Perspective by Denholm et al.
    ( http://www.sciencemag.org/cgi/content/short/297/5590/2222 ),
    the findings "have important implications for understanding how resistance evolves and the threats it poses to sustainable pest and disease management."
  • antibiotic resistance
    • recent news report http://news.bbc.co.uk/hi/english/health/newsid_1286000/1286273.stm
    • Centers for Disease Control (CDC) brief background on antibiotic resistance and how to prevent it  http://www.cdc.gov/drugresistance/community/ 
    • A much more in-depth report
      http://www.parliament.the-stationery-office.co.uk/pa/ld199798/ldselect/ldsctech/081vii/st0701.htm
    • antibiotic resistant bacteria strains as markers in genetically modified food crops. http://www.foodsafetynetwork.ca/gmo/antresgm.pdf 
    • http://www.whybiotech.com/en/pressrel/con715.asp?MID=18
    • http://www.foodsafetynetwork.ca/gmo/antresgm.pdf what individuals can do
    • primer on antibiotics m http://helios.bto.ed.ac.uk/bto/microbes/penicill.htm
    • easy-to-read explanation of antibiotic resistance http://people.ku.edu/~jbrown/resistance.htm
    • This set of links on antibiotic resistance are from The NSDL Scout Report for the Life Sciences, Copyright Internet Scout Project 1994-2002. http://scout.cs.wisc.edu/ 
  • 10 Adams and 18 Eves: http://www.nytimes.com/library/national/science/050200sci-genetics-evolution.html
  • http://www.nytimes.com/library/national/science/061300sci-anthro-neanderthal.html
  • fossils: http://www.nytimes.com/library/national/science/122199sci-archaeo-flowers.html
  • How did it all begin?  http://www.nytimes.com/library/national/science/082500sci-life-origins.html
  • hybrid inviability http://helix.nature.com/nsu/000504/000504-9.html
  • sympatric character displacement http://www.sciencemag.org/content/vol288/issue5467/twil.shtml#288/5467/773g (summary) & http://www.pnas.org/cgi/content/full/97/8/4106
  • effect of highways on gene flow: http://www.enn.com/news/enn-stories/2000/08/08072000/s_30220.asp?P=1
  • fast evolution of guppies:   http://www.eurekalert.org/pub_releases/1997-03/NSF-NSSS-270397.php 
  • does sex evolve?   http://www.eurekalert.org/pub_releases/1997-07/WFU-EAFF-300797.php 
  • Why do elephants have grandmothers?  http://www.nytimes.com/2001/04/24/science/24OBSER-2.html 
  • Artificial selection for tame foxes: http://www.nytimes.com/library/national/science/033099sci-foxes.html
  • sexual selection: http://www.nytimes.com/library/national/science/053000sci-conversation-miller.html
  • experiment on egg size http://helix.nature.com/nsu/000601/000601-8.html
  • new empirical evidence for natural selection http://www.sciencemag.org/cgi/content/full/287/5451/306
  • speed of evolution http://www.sciencemag.org/cgi/content/full/287/5451/308
  • commentary on both: http://www.sciencemag.org/cgi/content/full/287/5451/207a
  • Why peppers are hot: http://www.sciencemag.org/cgi/content/full/285/5431/1198
  • When ants marry their close relatives, their offspring reach puberty later and die earlier: http://www.sciencemag.org/cgi/content/full/285/5429/891
  • Sex and the Single Cockroach:  http://www.sciencemag.org/cgi/content/full/285/5427/518 (It's just after the giraffe story, which you could read too.)
  • the latest molecular news is always available at http://science.bio.org/ 
•  
• PROFESSIONAL SOURCES

• Evolution (a professional journal) http://evol.allenpress.com/evolonline/ 
• Evolution for Teachers:  http://evolution.berkeley.edu/evosite/evohome.html
• Papers from an NAS Colloquium on Genetics and the Origin of Species
• The following articles from Science Magazine require you to register, which takes a little extra time.  You can read recent articles also in the paper version of Science in the library.  Look for the date of the issue at the end of the "URL." 
  • 2001 Human Migration Issue of Science http://www.sciencemag.org/content/vol291/issue5509/#specialintro 
  • 1999 Evolution Issue of Science:

  • A few genes coding for big adaptations may be all that's needed for reproductive isolation and therefore speciation:  http://www.sciencemag.org/cgi/content/full/284/5423/2106a
  • field studies highlight the importance of ecology in the formation of species:   http://www.sciencemag.org/cgi/content/full/284/5423/2106
  • Documenting Speciation:  http://www.sciencemag.org/cgi/content/full/286/5440/681f
  • AND OTHERS

  • Hybrid infertility and speciation (enhanced): www.sciencemag.org/cgi/content/full/282/5390/889
  • The latest (2002) on Darwin's Finches:  http://evol.allenpress.com/evolonline/?request=get-document&issn=0014-3820&volume=056&issue=06&page=1240 
  • Homeobox gene may cause hybrid male sterility: http://www.eurekalert.org/releases/uchi-sooos.html
  • Sympatric speciation in blue tits:  http://www.sciencemag.org/cgi/content/full/285/5432/1399) (human news release version:  http://www.academicpress.com/inscight/09011999/grapha.htm)
  • But evidence for allopatric speciation in Mexican birds: http://www.sciencemag.org/cgi/content/full/285/5431/1190a
  • Testing a gene flow hypothesis; parapatric speciation of tropical birds:    http://sciencenow.sciencemag.org/cgi/content/full/1997/620/3    or  http://www.sciencemag.org/cgi/content/summary/276/5320/1791
  • And another gene flow hypothesis in ants:  http://sciencenow.sciencemag.org/cgi/content/full/1996/1016/2
  • dog evolution http://www.sciencemag.org/cgi/content/short/298/5598/1540
  • do males mutate faster than females? http://sciencenow.sciencemag.org/cgi/content/full/1997/930/1
  • And why are males more likely to be larger?:  http://www.sciencemag.org/cgi/content/full/282/5390/889
  • EVOLUTIONARY GENETICS:  Enhanced: The Causes of Haldane's Rule (the article is difficult, but it contains great links to other information)  http://www.sciencemag.org/cgi/content/full/282/5390/889
  • Have human beings evolved cooperative behavior?  http://www.sciencemag.org/cgi/content/summary/276/5320/1816
  • Speciation Speed:  http://www.sciencemag.org/cgi/content/summary/277/5332/1622
  • Kin selection -- the cooperative behavior shown between genetically-related animals -- has been the subject of intense debate among scientists studying the evolution of social behavior. Do animals actively choose to "stick to their own", or is their altruism merely a side effect of some other factor like living in close proximity? 
    •  (http://www.sciencemag.org/cgi/content/short/300/5627/1947):  many carrion crows stay close to home once they have matured, some disperse and visit other groups, where they compete for mates. However, DNA microsatellite data showed that in most cases, these wandering crows permanently join and cooperate with groups of related individuals, regardless of their proximity to the territory where they were born.
    • http://www.sciencemag.org/cgi/content/short/300/5627/1949), lizards chose to cooperate with other lizards that were unrelated, but similar in both appearance and genetic make-up. 
    • Perspective (http://www.sciencemag.org/cgi/content/short/300/5627/1887