River Out of Eden


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I developed this powerpoint when I taught River Out of Eden by Richard Dawkins. Most of the students found Dawkins to be fascinating, but they weren't so hot on the actual book.

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River Out of Eden

  1. 1. River Out of EdenA Look at Richard Dawkins and the Gene Theory of Evolution Bertolino--Mosaic 852-River Out of Eden 1
  2. 2. Dawkins Quoted• For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.• If you want to do evil, science provides the most powerful weapons to do evil; but equally, if you want to do good, science puts into your hands the most powerful tools to do so.• The world and the universe is an extremely beautiful place, and the more we understand about it the more beautiful does it appear.• There are all sorts of things that would be comforting. I expect an injection of morphine would be comforting... But to say that something is comforting is not to say that its true.• Theres this thing called being so open-minded your brains drop out. Bertolino--Mosaic 852-River Out of Eden 2
  3. 3. It Gets Better!• It is an article of passionate faith among "politically correct" biologists and anthropologists that brain size has no connection with intelligence; that intelligence has nothing to do with genes; and that genes are probably nasty fascist things anyway.• The likelihood is that, in 100,000 years time, we shall either have reverted to wild barbarism, or else civilization will have advanced beyond all recognition--into colonies in outer space...• There may be fairies at the bottom of the garden. There is no evidence for it, but you cant prove that there arent any, so shouldnt we be agnostic with respect to fairies?• What are all of us but self-reproducing robots? We have been put together by our genes and what we do is roam the world looking for a way to sustain ourselves and ultimately produce another robot child. Bertolino--Mosaic 852-River Out of Eden 3
  4. 4. Some Background on Dawkins Dawkins was an Assistant Professor of Zoology at the University of California, Berkeley from 1967 to 1969. In 1970 he was appointed a Lecturer, and ten years later he was appointed a Reader in Zoology at Oxford University. (For readers from the USA a "Reader" in a British university is approximately equivalent to an "Associate Professor" or "Full Professor" in the US.)• In 1995, he was appointed Simonyi Professor for the Public Understanding of Science at the University of Oxford. This position was endowed by Charles Simonyi with an express intention that Dawkins be its first holder. He has been a fellow of New College, Oxford since 1970. (A fellow is part of the governing body of the university.)• Education, positions and degrees• 1954-1959 Oundle School• 1959-1962 Balliol College, Oxford University• 1962-1966 Research Student, Oxford University (D.Phil., 1966)• 1965-1967 Research Assistant to Professor N.Tinbergen FRS• 1967-1969 Assistant Professor of Zoology, University of California, Berkeley• 1969-1970 Senior Research Officer, Department of Zoology, Oxford• 1970-1990 University Lecturer (US: Adjunct Professor) in Zoology, and Fellow of New College, Oxford• 1989 D.Sc. (Oxford)• 1990-1995 Reader in Zoology (US: "Associate Professor" or "Full Professor"), Oxford University• 1995-2008 Charles Simonyi Professor of the Public Understanding of Science, University of Oxford, and Professorial Fellow of New College Bertolino--Mosaic 852-River Out of Eden 4
  5. 5. His Books• Richard Dawkins has published a vast range of material.• The Selfish Gene (1976)• The Extended Phenotype (1982)• The Blind Watchmaker (1986)• River Out of Eden (1995)• Climbing Mount Improbable (1996)• Unweaving the Rainbow (1997)• A Devil’s Chaplain (2003)• The Ancestor’s Tale (2004)• The God Delusion (2006) He is best known for this book.• The Greatest Show on Earth (2009) Bertolino--Mosaic 852-River Out of Eden 5
  6. 6. Important Terms• Genes: working subunits of DNA. Each gene contains a particular set of instructions, usually coding for a particular protein.• Ancestor: a person from whom one is descended. In biology it is the actual or hypothetical form or stock from which an organism has developed or descended.• Utility Function: an economic term—Dawkins defines it as “that which is maximized.”(103) He writes: Utilitarians strive to maximize the greatest number”(104) Dawkins sees natural selection as using genetic codes as a method to strengthen individual species—it has a utility or useful function.• Reverse Engineering: Dawkins takes this term from Darwin’s Dangerous Idea by Daniel Dennett. It is a reasoning technique. He writes: “You are an engineer, confronted with an artifact you…don’t understand. You make the assumption that it was designed for some purpose….You analyze the object with a view to working out what problem it would be good at solving.” (103)• Genetic Drift: the random change in the genetic composition of a population due to chance events causing unequal participation of individuals in producing succeeding generations. Along with natural selection, genetic drift is a principal force in evolution.• Meme: the basic building blocks of our minds and culture, in the same way that genes are the basic building blocks of biological life.• The idea of memetics is in extending Darwinian evolution to culture. There are several conclusions from doing that, one of which is the ability to predict that ideas will spread not because they are "good ideas", but because they contain "good memes" such as danger, food and sex that push our evolutionary buttons and force us to pay attention to them. Dawkins applies the term in his preceding book, The Selfish Gene. Bertolino--Mosaic 852-River Out of Eden 6
  7. 7. More Terms in River Out of Eden• Self-replicate: the ability to use surrounding materials to make exact copies of itself.• River of DNA: a metaphor to indicate the gradual flow of geological time in which life forms share their genetic codes as an improvement for each species.• DNA: deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria .• Mitochondria: membrane-bound cell organelles (mitochondrion, singular) that generate most of the chemical energy needed to power the cells biochemical reactions. Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP). Mitochondria contain their own small chromosomes. Generally, mitochondria, and therefore mitochondrial DNA, are inherited only from the mother.• Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. The remaining genes provide instructions for making molecules called transfer RNAs and ribosomal RNAs , which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins. Bertolino--Mosaic 852-River Out of Eden 7
  8. 8. Genetic DriftMitochondrial Dna Bertolino--Mosaic 852-Rver Out of Eden 8
  9. 9. Bertolino--Mosaic 852-River Out of Eden 9
  10. 10. Utility FunctionReverse Engineering Bertolino--Mosaic 852-River Out of Eden 10
  11. 11. Chapter 1: The Digital River• How do we understand the term digital?• 1. Binary storage of information as 1s and 0s• 2. Having to do with digits (fingers or toes),performed with a finger- Property of representing values as discrete numbers rather than a continuous spectrum.• 3. Displaying numbers rather than scale positions; "digital clock”-- A circuit or device that represents magnitudes in digits; "digital computer“.• The river of DNA is a river of coded genetic information that flows downward—it is linear like time. The river gathers more DNA to create more genetic information.• The metaphor is designed to explain ancestry and descents. We descend down the river, but we begin with a source—the origin of the river . That would be our original ancestor. Bertolino--Mosaic 852-River Out of Eden 11
  12. 12. The DNA River and Eve Consider an extremely prolific woman living today. She has many daughters and takes a vacation to a remote Caribbean island for a week. During the same week a plague of a mutated Ebola virus sweeps the Earth and drastically decreases the fecundity of all living women. Not only that, the viral infection also changes the genome of these women so that the daughters they give birth to will inherit this reduced fecundity. This means that far more than average of their fetuses will undergo abortions (or, in a somewhat kinder scenario, their female fetuses will be aborted more often than male ones).• Only this one woman and her daughters who were off in this Caribbean island are safe from the viral plague. Also assume that the viral plague consumes itself within that fateful week. This woman and her daughters are now free to breed in a world where their reproductive potential far outstrips that of every other woman alive (and to be born of these women). Soon, almost every one on Earth will be related in some fashion to this one woman. Finally, when the last woman who was born to one of the matrilineal descendents of an infected woman dies, the non-infected Caribbean tourist takes on the title of the new Mitochondrial Eve. Every human alive on Earth at that point in time is now related via the mitochondrial line to her.• But consider this new twist. Suppose a group of astronauts (men and women) were sent off into space during the infection week, and were thus not infected themselves. After many centuries in a Moon or Mars colony, they returned to Earth. At that time, suddenly, the title of Mitochondrial Eve would revert back to our own ME. The humans alive on the Earth at that time would all share their mitochondrial DNA with an earlier common ancestor.• As an exercise, try to eliminate just one phrase of the definition of the ME and see what happens. The key terms are most-recent, common ancestor, humans alive today, matrilineal descent.• (see previous slide for source) Bertolino--Mosaic 852-River Out of Eden 12
  13. 13. Chapter 2:All Africa and Her Progeny-- Mitochondrial Eve Mitochondrial Eve refers to the most recent common matrilineal ancestor from whom all living humans are descended. Passed down from mother to offspring, all mitochondrial DNA (mtDNA) in every living person is directly descended from hers. Mitochondrial Eve is the female counterpart of Y-chromosomal Adam, the patrilineal most recent common ancestor, although they lived thousands of years apart.• Mitochondrial Eve is generally estimated to have lived around 200,000 years ago, most likely in Africa, when Homo sapiens (us) were developing as a species separate from other human species. Bertolino--Mosaic 852-River Out of Eden 13
  14. 14. Another interpretation of Eve—Lucy as the original ancestor. Bertolino--Mosaic 852-River Out of Eden 14
  15. 15. More On M. Eve• The ME represents that woman whose mitochondrial DNA (with mutations) exists in all the humans now living on Earth. That does not mean that she is our lone woman ancestor. We have ancestors who are not via matrilineal descent. For example, our fathers mother (who did pass on her mitochondrial DNA to her daughters) is an example of an ancestor who is not matrilineal to us. However, she did exist at one time and was probably of the same age as our mothers mother, who is a matrilineal ancestor of ours and from whom we got our mitochondrial DNA.• The term Mitochondrial Eve itself is a title given retroactively to a woman. Often (and as is certainly the case with the ME that we are discussing) the conferring of the title occurs many hundreds of thousands of years after the death of the woman in question.• ME lived with many other humans (men and women); she was certainly not alone. When she was alive, she was most certainly NOT the Mitochondrial Eve. The title at that time was held by a distant ancestor of hers (and of the many humans who were her contemporaries).• The existence of the Mitochondrial Eve is NOT a theory; it is a mathematical fact (unless something like a multiple-origins theory of human evolution i.e. the human species arose independently in different geographically separated populations, and that the present-day ease of interbreeding is the result of a remarkable convergent evolution, is true.• (same source—see previous slide) Bertolino--Mosaic 852-River Out of Eden 15
  16. 16. What Does This Mean?• The name Eve, in retrospect, is perhaps the worst possible name to give to the entity in question. I believe that this is probably the cause of so much confusion in understanding what the significance of this entity is. People think that this title has some deep theological or religious consequences. Nothing of that sort.• Someone you come across who claims that the bible (or the book of Genesis) has been validated by the discovery of the Mitochondrial Eve, is talking crap---you should feel free, and even obligated, to tell them so. The Mitochondrial Eve of 200,000 years ago (ME for short henceforth) is NOT our common ancestor, or even common genetic ancestor. She is the most- recent common ancestor of all humans alive on Earth today with respect to matrilineal descent. That may seem like a mouthful, but without even a single one of those qualifying phrases, any description or discussion of the ME reduces to a lot of nonsense.• (taken from “What, if anything, is a Mitochondrial Eve?” by Krishna Kunchithapadam Bertolino--Mosaic 852-River Out of Eden 16
  17. 17. One Explanation (Discussed in Class) Consider all the humans alive today on Earth. Put them into a set S. Next, consider the set of all those women who were the mothers of the people in the set S. Call this set S. A few observations about this new set S. It consists of only women (while set S consists of both men and women)---this is because we chose to follow only the mother-of relationship in going from set S to set S. Also note that not every member of set S needs to be in set S---set S consists of all people living today, while some of the mothers of living people could have died, they would be in set S but not in set S. Third, the size of set S is never larger than the size of set S. Why? This is because of the simple fact that each of us has only one mother. It is however overwhelmingly more likely that the size of set S is much smaller than that of set S---this is because each woman usually has more than one child.• Repeat the process of following the mother-of relationship with set S to generate a new set S. This set will consist of only women, and will be no larger (and very likely smaller) than set S. Continue this process. There will come a point when the set will consist of smaller and smaller number of women, until we finally come to a single woman who is related to all members in our original set via the transitive-closure of the mother-of relation. There is nothing special about her.• So there must exist a single woman whose is the matrilineal most-recent common ancestor of every in set S. A few others points to keep in mind. One might say that if each woman has only a single daughter (and however many sons), the size of the sets will be the same as we extrapolate backwards. But also note that this backwards mathematical extrapolation is an extrapolation into the past. This process cannot be continued indefinitely because the age of the Earth, life on Earth, and the human species is finite (this argument comes from Dawkins).• ( taken from Daniel C. Dennett, Darwins Dangerous Idea) Bertolino--Mosaic 852-River Out of Eden 17
  18. 18. Chapter 3: Do Good by Stealth• The chapter’s name comes from a quote by Alexander Pope, the 18th century English poet:• Do good by stealth, and blush to find it fame.• It is another way of suggesting that the left hand should not know what the right hand is doing.• For Dawkins, it points to gradualism in evolution. As he writes:• Do good by stealth. A key feature of evolution is its gradualness. This is a matter of principle rather than fact….Evolution is very possibly not…always gradual. But it must be gradual when it is …used to explain the coming of existence of complicated , apparently designed objects, like eyes. For if it is not gradual…it ceases to have any explanatory power at all. Without gradualism…we are back to miracle which is simply a synonym for the total absence of explanation. (83) Bertolino--Mosaic 852-River Out of Eden 18
  19. 19. Chapter 4: God’s Utility Function See reverse engineering and utility function on the earlier slides. Dawkins discusses the overall design of nature which is no design at all. He writes: “We cannot admit that things may be neither good nor evil, neither cruel nor kind, but simply callous—indifferent to all suffering, lacking all purpose.” (96)This chapter serves as a prelude to his disdain for any God belief system.• He writes: “So long as DNA is passed on, it does not matter who or what gets hurt in the process.” (131)• He discusses the argument of senescence-the science of aging:• The evolutionary theory of aging proposes two models for how aging can evolve. One derives from ideas in which genetic drift and mutation accumulation lead to the loss of late-acting beneficial genes or to the appearance of late-acting harmful genes. In another model, aging evolves due to the multiple effect of genes that are beneficial early in life and then harmful at late ages. At present, both theories are widely accepted and they are not mutually exclusive, yet Dawkins seems more convinced by the latter.* (source:” The Evolutionary Theory of 852-River Out of Eden de Magalhães, Ph.D) Bertolino--Mosaic Aging” by João Pedro 19
  20. 20. Chapter 5: The Replication Bomb• Supernova: a star suddenly flares without warning—increases in brightness by a factor of many billions, then dies away to a former remnant of itself. (135)• Replication bombs: stars that “go information”-the triggering event of a replication bomb is the spontaneous arising of self-replicating yet variable entities. It comes from exponential growth of an object that copies itself. Example: “Once you have a self-replicating object, you will soon have two.” (137)• See page 138: “We have no direct evidence of the replication event that initiated the proceedings on this planet. We can only infer that it must have happened…it began as a chemical event.”• See page 145:“Our replication bomb has taken a few billion years to reach the radio threshold—the moment when a proportion of the information overflows from the parent world and …bathes the world with pulses of meaning.” Bertolino--Mosaic 852-River Out of Eden 20
  21. 21. Appearance of a SupernovaSupernova Explosion Supernova Explosion Bertolino--Mosaic 852-River Out of Eden 21
  22. 22. Big Bang TheoryBertolino--Mosaic 852-River Out of Eden 22
  23. 23. Replication Bomb—Disease asExample—HIV and Hepatitis C Bertolino--Mosaic 852-River Out of Eden 23
  24. 24. Source of the book titleGenesis 2:8-10 Rivers in Genesis• Now the LORD God had planted a garden in the east, in Eden; and there he put the man he had formed.• 9 And the LORD God made all kinds of trees grow out of the ground—trees that were pleasing to the eye and good for food. In the middle of the garden were the tree of life and the tree of the knowledge of good and evil.• 10 A river watering the garden flowed from Eden; from there it was separated into four headwaters. Bertolino--Mosaic 852-River Out of Eden 24