1. Human Evolution

2. I. What are humans related to?

3. Human Evolution I. What are humans related to? - Morphologically similar to apes

4. Human Evolution I. What are humans related to? - Morphologically similar to apes - hands, binocular vision (Primates) No tail

5. Human Evolution I. What are humans related to? Apes

6. Human Evolution I. What are humans related to? Apes II. How do we differ?

7. Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect)

8. Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning)

9. Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio

10. Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio

11. Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio - shorter arms/body ratio

12. Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio - shorter arms/body ratio - less hair

13. Human Evolution I. What are humans related to? Apes II. How do we differ? - Morphologically Human Chimp Gorilla Orangutan Gibbon

14. Human Evolution I. What are humans related to? Apes II. How do we differ? - Genetically: Big Surprize! Human Chimp Gorilla Orangutan Gibbon

15. Human Evolution I. What are humans related to? Apes II. How do we differ? - Genetically: Big Surprize! Human Chimp Gorilla Orangutan Gibbon < 1% difference in gene sequence

16. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see?

17. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, some genes have big effects. These are regulatory genes, acting during development. They influence the expression of lots of other genes…

18. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, some genes have big effects. These are regulatory genes, acting during development. They influence the expression of lots of other genes… - Can we test this hypothesis? Do the differences correlate with developmental effects?

19. - Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratiosmaller Smaller jaw/head ratiolarger Shorter limb/body ratiolonger Less hairmore hair Better learningpoorer learning

20. - Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratiosmaller Smaller jaw/head ratiolarger Shorter limb/body ratiolonger

21. - Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratiosmaller Smaller jaw/head ratiolarger Shorter limb/body ratiolonger Less hairmore hair Better learningpoorer learning Human-likeApe-like

22. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, if the small change is in developmental genes, they can have BIG effects…humans might be a type of ape that didn’t grow up… The ways we differ supports this hypothesis…

23. Yes, if the small change is in developmental genes, they can have BIG effects…humans might be a type of ape that didn’t grow up… Primate developmental trajectory Chimp Small changes in development, especially if they occur early in development, can result in big effects. Human

24. What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory BeniaminovBeniaminov A, Westhof E, and Krol A. 2008.WesthofKrol Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

25. What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory - nearby genes associated with transcriptional regulation and neurodevelopment are upregulated in humans. BeniaminovBeniaminov A, Westhof E, and Krol A. 2008.WesthofKrol Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

26. What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory - nearby genes associated with transcriptional regulation and neurodevelopment are upregulated in humans. - only 2 changes in sequence between chicks and chimps; 18 between chimps and humans… “HAR” stands for “human accelerated region” – changing more rapidly than drift can explain… why? Selection. BeniaminovBeniaminov A, Westhof E, and Krol A. 2008.WesthofKrol Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

27. What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory - nearby genes associated with transcriptional regulation and neurodevelopment are upregulated in humans. - only 2 changes in sequence between chicks and chimps; 18 between chimps and humans… “HAR” stands for “human accelerated region” – changing more rapidly than drift can explain… why? Selection. -Changes result in a profound change in RNA structure and, presumably, binding efficiency. BeniaminovBeniaminov A, Westhof E, and Krol A. 2008.WesthofKrol Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

28. Two distinct experimentally supported secondary structure models for HAR1 RNAs. Beniaminov A et al. RNA 2008;14:1270-1275 Copyright © 2008 RNA Society HUMAN CHIMP

29. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors?

30. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? Yes. Just where evolution predicts they should be (After other monkeys and apes, before humans and existing apes).

31. Molecular clock analyses

32. Science, Nov 19, 2004 Pierolapithecus catalaunicus 12-13 mya: oldest ‘great ape’

33. ‘apes’ – no tail

34. V. Are there common ancestors? - Fossil and genetic analysis independently predicted a common ancestor between humans and chimps lived 5-8 million years ago. Chimpanzee Human Homo sapiens

35. V. Are there common ancestors? - Fossil and genetic analysis independently predicted a common ancestor between humans and chimps lived 5-8 million years ago. Chimpanzee Human Homo sapiens Sahelanthropus tchadensis – discovered in Chad in 2001. Dates to 6-7 mya. Only a skull. Is it on the human line? Is it bipedal? Probably not (foramen magnum). Primitive traits, as a common ancestor might have.

36. Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? V. Are there intermediate links to modern humans?

37. - yes, and in a nearly continuous sequence…. Chimpanzee Human Homo sapiens Australopithecus afarensis Australopithecus africanus Homo habilis Homo erectus

38. V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya

39. V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya

40. V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya “slender” species

41. V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya “slender” species “robust” species

42. V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya Primitive, bipedal species

44. Orrorin tugenensis: 5.6-6.2 mya. Discovered in 2000 by Brigitte Senut. Processes on femus suggest bipedality in this forest-dwelling species, refuting the savannah-bipedality link. Some suggest the femur is more humanlike than those of Australopithecines, suggesting those are a side group in human evolution.

45. Ardipithecus kadabba: 5.6 mya. Discovered in 2004 by Haile-Sailasse, Gen Suwa, and Tim White. Initially thought to be chronospecies of A. ramidus, tooth size in recent fossils suggested a new species.

46. Ardipithecus ramidus: 4.3-4.5 mya. Discovered in 1994 by Haile-Sailasse, Suwa, and White, with the most complete fossils were not described until 2009. Arboreal, but facultatively bipedal. Grasping toes. video

48. Australopithecus anamensis: 3.9-4.4 mya. About 100 fossils, from an estimated 20 individuals; all from the Lake Turkana region of east Africa. Found in 1965, 1987, 1995, and 2006, it was only in 1995 when Meave Leakey distinguished it from other Australopithecine species. Probably the direct ancestor of A. afarensis. Dr. Meave Leakey is spouse of Dr. Richard Leakey, son of Louis and Mary Leakey – discoverers of several ancient hominids at Olduvai Gorge.

49. Australopithecus afarensis: 2.8-3.9 mya. A femur discovered in 1973 by Donald Johansson suggested an upright gait, confirmed by his discovery in 1974 of the ‘Lucy” specimen. Also, the Laetoli prints (found by Mary Leakey) were probably made by A. afarensis, and in 2006, a juvenile A. afaresis was found.

50. And, as we’ve discussed, Australopithecus afarensis walked erect. video

51. And, as we’ve discussed, Australopithecus afarensis walked erect.

52. A. Afarensis prints at Laetoli, approximately 3.56 myr, were made by an obligate biped: - heel strike. - Lateral transmission of force from the heel to the base of the lateral metatarsal. - A well-developed medial longitudinal arch. - Adducted big toe, in front of the ball of the foot and parallel to the other digits. - A deep impression for the big toe commensurate with toe-off.

54. Australopithecus bahrelghazali: 3.6 mya; discovered in Chad in 1993 by Michel Brunet – who won’t release it for others to study. Most paleontologists suggest it is within the range of variation for A. afarensis. First australopithecine outside of east Africa.

55. Kenyanthropus platyops: 3.2-3.5 mya – Discovered by Meave Leakey’s team at Lake Turkana; most dispute it warrants another genus, and some even include it in A. afarensis.

56. Australopithecus africanus: 2-3 mya, discovered by Raymond Dart in South Africa in 1924 – the ‘Taung child’. Then, in 1947, Robert Broom found a skull he classified as Plesianthropus, but was grouped with A. africanus.

57. Australopithecus garhi: 2.5-2.6 mya; discovered by Asfaw and White in 1996, but the skull below was discovered by Haile-Selasse in 1997. The tooth morphology is a bit different from A. afarensis and A. africanus, being much larger than even the robust forms. There are associated stone tools!

58. Australopithecus sebida: 1.9 mya, describe in 2010 by LE Berger; it has many characteristics like A. africanus, but also similar to genus Homo.

59. Paranthropus aethiopicus: 2.5-2.7 mya, discovered by Alan Walker and Richard Leakey, the “black skull” is one of the most imposing hominid fossils there is! Aside from the high cheekbones and the sagittal crest, it has similar proportions to A. afarensis and is probably a direct descendant. It probably gave rise to the “robust” lineage of Paranthropus.

60. Paranthropus boisei: 1.2-2.6 mya. Discovered by Mary Leakey in Olduvai Gorge in 1959, it was originally classified as Zinjanthropus and nicknamed “Zinj” or “nutcracker man” because of the large grinding molars.

61. Paranthropus robustus: 1.2-2.0 mya. Discovered in South Africa in 1938 by Robert Broom.

62. Homo habilis: 1.4-2.3 mya, discovered by Louis and Mary Leakey, in association with stone tools. “Handy man”. Longer arms and smaller brain than other members of the genus.

63. Homo rudolphensis: 1.9 mya; Discovered by Richard and Meave Leakey’s team. Different from H. habilis, yet a contemporary. Either may be ancestral to recent Homo.

64. Homo georgicus: 1.7 mya; the oldest hominid fossils found outside of Africa – found in Dmanisi, Georgia, in 1999. Thought to be a potential intermediate between H. habilis and H. ergaster/H. erectus.

65. Homo erectus: 0.2-1.8 mya; originating in Africa, but then leaving for Asia (Peking and Java Man). Discovered in Java by Eugene Dubois in 1891. Certainly one of the most successful hominid species in history; perhaps lasting as relictual species on islands in Indonesia as: Homo floresiensis: 94,000-13,000 years, discovered by Mike Mormood on the island of Flores. Shoulder anatomy is reminiscent of H. erectus, but could be an allometeric function of the small size (3 ft).

66. Homo ergaster (H. erectus): 1.3-1.8 mya, the most complete fossil hominid skeleton was discovered in 1984 by Alan Walker who called it “Turkana Boy”. Some consider this species intermediate to H. habilis and H. heidelbergensis/H. sapiens, leaving H. erectus as a distinct Asian offshoot of the main line to H. sapiens. However, most paleontologists suggest that H. ergaster is the African ancestor – even a chronospecies or population - of H. erectus, which is ancestral to more recent Homo species.

68. Homo cepranensis: 350,000-500,000 years old; discovered by Italo Biddittu in 1994 in Italy. It is just a skull cap, but seems to be intermediate between H. erectus and H. heidelbergensis.

69. Homo antecessor: 800,000-1.2 mya; fossils from 20 individuals found in Spain in 1994-5; may be H. heidelbergensis or an intermediate between it and H. ergaster. Homo heidelbergensis: 250-600,000 in Europe and Africa; ancestral to H. neaderthalensis and H. sapiens; may have buried their dead. Homo rhodesiensis: 125-300,000; may be H. heidelbergensis or intermediate to it and H. sapiens.

70. Homo neaderthalensis: 30,000-150,000; first discovered in 1829. Descended from H. heidelbergensis. Homo sapiens idaltu: 160,000 – oldest Homo sapiens fossil – found in Africa in 2003… Afar valley.

74. VIII. And what of our species? - From Africa 200,000 years ago (earliest fossils, genetic variability, etc.) (Brazil)

76. VIII. And what of our species? - From Africa 200,000 years ago (earliest fossils, genetic variability, etc.) - Bands of hunter gatherers

77. VIII. And what of our species? - From Africa 200,000 years ago (earliest fossils, genetic variability, etc.) - Bands of hunter gatherers - Cave Art about 30,000 years ago

78. VIII. And what of our species? - From Africa 200,000 years ago (earliest fossils, genetic variability, etc.) - Bands of hunter gatherers - Cave Art about 30,000 years ago - 14,000 years ago, bands settled in different areas of the globe and began to grow local crops. First Agricultural Revolution….

79. Where and when: Sahel? West Africa? Ethiopia ? Fertile Crescent China New Guinea Andes Amazon? Mesoamerica Eastern U. S.

80. 5.0 mya 1.75 mya tools art 0.2 mya burial 75,000 agricultur e 14,000 …to chimps 99.6% before art HUMAN PREHISTORY – Where did humans come from?

81. And Now… The Anthropocene: - 14,000 years to present. Score of human impact due to land transformation, soil, water, and air quality. (Each biome has it’s own scale, however, so they are not explicitly comparable).

83. “The pale blue dot” …. Earth from the Voyager spacecraft, > 4 billion miles away http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2148

84. http://www.solstation.com/stars/earth.htmhttp://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-mars.html

86. http://www.thew2o.net/#

87. http://www.misterteacher.com/rainforestwebquest.html

88. EarthMars CO 2 0.035%95% N2N2 77%2.7% H2OH2O1%0.007% Ar0.93%1.6% O2O2 21%trace

89. http://science.kennesaw.edu/~jdirnber/BioOceanography/Lectures/LecPhysicalOcean/LecPhysicalOcean.html

92. Earth History 4.5 bya: Earth Forms4.0 bya: Oldest Rocks3.4 bya: Oldest Fossils 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 0.5 bya: Cambrian0.24 bya:Mesozoic0.065 bya:Cenozoic 4.5 million to present (1/1000th of earth history)

93. All genera “well described” genera The “big five” Mass Extinction Events http://en.wikipedia.org/wiki/File:Phanerozoic_biodiversity_blank_01.png Millions of Years Ago Thousands of Genera

94. Permian mass extinction: 96% of all marine species and 70% of terrestrial vertebrate species (% of Genera)

95. WHY?

101. http://science.nationalgeographic.com/science/prehistoric-world/mass-extinction/

102. http://we.vub.ac.be/~dglg/Web/Claeys/Chicxulub/Chixproject.html ecological collapse Almost all animals over 25kg (~55 lbs) went extinct. (The things that require the most energy to survive)

103. BIODIVERSITY NOW http://www.coral.org/node/3230

104. Millenium Ecosystem Assessment (2006) http://englishontour.blogspot.com/2011/03/beetles.html

105. http://www.illuminatedorigin.com/The_Illuminated_Origin_of_Species/Blog/Entries/2011/9/22_Beetles!.html http://www.sbs.utexas.edu/jcabbott/abbottlab/ Detritivores Pollinators Insect predators Herbivores

106. http://www.dendroboard.com/forum/photography/42636-incredible-costa-rican-euglossine-bees.html Pollinators Insect Parasitoids (lay eggs on other insects) Insect Predators

107. Malagasy Sunset Butterfly Jewel Bug http://magicbelles.com/flutterbudclub/special-wonders/beetles http://buggirl.tumblr.com/post/12568644622/bugs-that-break-the-rules-the- madagascar-sunset http://www.brisbaneinsects.com/brisbane_flies/images/PWC_8410.jpg Herbivores Pollinators Parasites Detritivores

108. http://www.trekearth.com/gallery/Africa/South_Africa/West/Eastern_Cape/Kob_Inn/photo915391.htm Herbivores Detritivores

109. http://www.paulsanghera.com/infonential-Contact.html http://www.flowersociety.org/Redwood-profile.htm PRODUCERS

110. Most vertebrate species are fishes http://www.elp.manchester.ac.uk/pub_projects/2003/MNZO0MLK/lecture1.htm

111. http://www.bbc.co.uk/nature/life/Blue_Whale http://freakz.info/2011/09/21/10-interesting-seahorse-facts/ http://ambergriscaye.com/critters/redeyedtreefrog.ht ml http://www.hodag.info/what%E2%80%99s-going-on-here- then-100 http://australian-animals.net/plat.htm http://www.pbase.com/image/37557333 Herbivores, Predators, Detritivores, Pollinators

112. But do we NEED all these species??

113. http://katherinegerdes.com/portfolio/11/rainy-day-jewels There’s a lot of redundancy in nature…

114. Are all species equally important? If not, which ones are critical?

115. with without

116. We don’t know which species are critical So we need to save them all to maintain ecosystem function

117. But what does biodiversity do??

118. 1) Biodiversity increases “productivity”... FOOD

119. Monoculture They all need the same things at the same concentrations; they compete.

120. MonoculturePolyculture Combinations of different plants can be planted at higher density, and they use different "niches" and coexist. Even if abundance of "most productive" species drops, this loss can be offset. They all need the same things at the same concentrations; they compete. “Niche Complementarity”

121. MonoculturePolyculture Nitrogen fixing legumes (beans) nutrify the soil, increasing the growth of other plants. And you have beans! without beans with beans They all need the same things at the same concentrations; they compete. “Positive Effects”

122. 2) Biodiversity improves ecosystem services Estimates of various Ecosystem Services - $U.S. trillions Ecosystem services Value (trillion $US) Soil formation17.1 Recreation3.0 Nutrient cycling2.3 Water regulation and supply2.3 Climate regulation (temperature and precipitation) 1.8 Habitat1.4 Flood and storm protection1.1 Food and raw materials production 0.8 Genetic resources0.8 Atmospheric gas balance0.7 Pollination0.4 All other services1.6 Total value of ecosystem services 33.3 Source: Adapted from R. Costanza et al., “The Value of the World’s Ecosystem Services and Natural Capital,” Nature, Vol. 387 (1997), p. 256, Table 2. TOTAL GLOBAL GNP (1997) = 18 trillion.

123. 3) Aesthetics and Inspiration: Biodiversity enriches our cultures

125. How is our biodiversity doing? Genetic diversity within species Species diversity in communities Ecosystem diversity

126. How is our biodiversity doing? Humans used hundreds of crop species worldwide; now 3 species (rice, wheat, corn) provide 60% of our calories from crop plants. According to the FAO of the UN, 70% of the genetic diversity of crop plants has been lost in the last 75 years as we’ve shifted to industrial farming and the use of GM strains.

127. How is our biodiversity doing? 2000 Pacific Island bird species (15% of global total) have gone extinct after human colonization 20 of the 297 mussel species in N.A. have gone extinct in the last 100 years; 60% are endangered 40 of 950 fish species in N. A. have gone extinct in the last century; 35% are threatened or endangered http://www.americanscientist.org/issues/pub/the-real-biodiversity-crisis/1 http://www.nps.gov/sacn/planyourvisit/st-croix- currents.htm?customel_dataPageID_206517=289024 http://www.fishdecoys.net/pages/LDC_Collection/BenzieJoDecoys.htm Yellow-finned cutthroat trout

128. How is our biodiversity doing? 1 in 4 mammal species is endangered 1 in 8 bird species is endangered 1 in 3 amphibian species is endangered 48% of primate species are threatened Data from: http://iucn.org/what/tpas/biodiversity/

129. How is our biodiversity doing? 35% of mangrove habitat has been lost in the last 20 years In the Caribbean, hard coral cover has declined from 50% to 10% in the last 20 years Since 2000, 232,000 sq miles of old growth forest have been lost (size of Texas).

131. WHY?

132. 7 billion in 2011 (12 years later)

133. http://news.mongabay.com/2011/1009-amazon_deforestation_revised.html 13,000 sq kilometers is about the size of Connecticut

134. http://mvh.sr.unh.edu/mvhinvestigations/old_growth_forests.htm Extent of Virgin Forest, Contiguous U. S.

136. Millenium Assessment 2006

137. 1 10 million? Humans use/control 40% of the ‘food’ produced on the planet.

138. Fragmentation

139. PLANTS HERBIVORES CARNIVORES LARGE AREA OF HABITAT Area Effects Fragmentation

140. HABITAT FRAGMENTATION Fragmentation

141. HABITAT FRAGMENTATION Fragmentation 1)Carnivores lost - (reduce diversity) 2)Herbivores compete – (reduce diversity) 3)Plants overgrazed – (reduce diversity)

142. We are a geological force, operating on an ecological timescale Mountaintop removal in West Virginia

143. We are a geological force, operating on an ecological timescale Gold mining in Peruvian Amazon

144. We are a geological force, operating on an ecological timescale

146. Hmmmm….

147. All genera “well described” genera The “big five” Mass Extinction Events http://en.wikipedia.org/wiki/File:Phanerozoic_biodiversity_blank_01.png Millions of Years Ago Thousands of Genera Sixth major mass extinction event - NOW

148. 22 May 2010 –Secretary-General Ban Ki-moon: “Biodiversity loss is moving ecological systems ever closer to a tipping point beyond which they will no longer be able to fulfill their vital functions.”

149. What Can We Do? We need to protect and preserve large intact, biodiverse ecosystems.

150. This is great, but it ain’t gonna do it…

152. We need to rethink our model of community… Development nature Development

153. We need to find out what’s out there!

154. We need to appreciate the societal and economic value of biodiversity Corporate Social Responsibility (CSR) http://www.justmeans.com/Stop-Loss-CSR-Biodiversity/28856.html “Protection of biodiversity should be the underlying reason for every CSR effort. Biodiversity loss is the most severe threat to human-wellbeing on the planet. It rates even higher than climate change and related problems…. The head of Deutsche Bank's Global Markets predicts that our current rate of biodiversity loss could see 6% of global GDP wiped out as early as 2050. The Economics of Ecosystems and Biodiversity executive summary (2010) The Economics of Ecosystems and Biodiversity executive summary (2010) reports that “over 50% of CEOs surveyed in Latin America and 45% in Africa see declines in biodiversity as a challenge to business growth. In contrast, less than 20% of their counterparts in Western Europe share such concerns”

156. If we recognize the grandeur of life, we might appreciate it…

157. If we appreciate it, we might value it…

158. If we value it, we might sustain it…

159. If we sustain it, we might be able to sustain our societies and economies, as well. ECONOMY SOCIETY ENVIRONMENT

160. If we don’t, we won’t… A few extinct animal species. Thylacine - 1936 Quogga - 1883 Golden Toad - 1989 Tecopa Pupfish - 1981 Yangtze River Dolphin - 2006 Vietnamese Rhinoceros - 2010

161. Study questions: In what two major ways does the earth differ from Mars? How have each of these differences influenced the dramatic loss of CO 2 from the earth atmosphere, relative to Mars? Dinosaurs went extinct because a meteor struck the earth and caused an ‘ecological catastrophe’ in which the animals with the greatest energy demand went extinct. Why is humanity similarly vulnerable with respect to the amount of resources we use, and the range of food we consume? What are the two main ways that we are causing the extinction of other organisms? Why is maintaining diversity important? (Brief answers on the next slides – try them yourselves first!!!!)

162. Study questions: In what two major ways does the earth differ from Mars? Lots of liquid water at the surface, and the presence of life. How have each of these differences influenced the dramatic loss of CO 2 from the earth atmosphere, relative to Mars? First, CO2 dissolves in water. Then, it is available to organisms that make shells and reefs out of calcium carbonate. This material accumulates as sedimentary deposits (Cliffs of Dover) in the lithosphere. Likewise, the evolution of photosynthesis (specifically the ‘light independent reaction’) allow CO2 in the atmosphere to be stored as glucose, cellulose, and other organic molecules. Although respiration and decomposition would return CO2 to the atmosphere, much of the organic remains have been preserved as fossil fuel deposits in sedimentary rocks – again representing a transfer of CO2 from the atmosphere to the lithosphere, mediated by living organisms.

163. Study questions: Dinosaurs went extinct because a meteor struck the earth and caused an ‘ecological catastrophe’ in which the animals with the greatest energy demand went extinct. Why is humanity similarly vulnerable with respect to the amount of resources we use, and the range of food we consume? We use 40% of the food produced on land. If there was an ecological catastrophe that reduced food production, we would feel it worse than other species. In addition, we get 60% of our calories from just three species!!! So, if a calamity befalls any of these three species, we will feel it. What are the three main ways that we are causing the extinction of other organisms? 1.Competition – we are consuming most the food. 2.This is largely by changing their habitats (prairie, forest, etc.) into our agricultural land. 3.Changing the climate faster than it has changed before, and faster than many species can adapt. Why is maintaining diversity important?

164. Study questions: Why is maintaining diversity important? Natural ecosystems provide ‘services’ upon which humanity depends, such as making food, cleaning the air, cleaning the water, stabilizing the climate, and fertilizing the soil. Ecology has shown that more diverse systems are more effective and efficient at performing these functions. Although there is redundancy in nature, we don’t yet know which species are the key ‘drivers’ of ecosystem function. As such, in order to maintain ecosystem function, we must ‘keep all the pieces’. As the percentage of endangered species in different groups shows, we aren’t doing such a great job at this. BUT! The first step in solving a problem is identifying it. Now we know. Now we must act.