Natural Selection Is Not Predictable

first_imgEvery once in awhile, biologists argue over whether evolution is predictable. The latest flap over stick insects sticks up for predictability, but flops.An international group of scientists, publishing in the journal Science, studied stick insects—those long, skinny walking insects that try to blend in with plants by mimicking twigs. In their paper, “Natural selection and the predictability of evolution in Timema stick insects,” they do their best to estimate the trajectory of these bugs. Laura Zahn, however, in a summary of the paper in the same issue of Science, has this to say:Evolution results from expected effects, such as selection driving alleles toward fixation, and stochastic effects, such as unusual environmental variation and genetic drift. To determine the potential to predict evolutionary change, Nosil et al. examined three naturally occurring morphs of stick insects (see the Perspective by Reznick and Travis). They wanted to determine which selective parameters could be used to foresee changes, despite varying environmental conditions. One morph fit a model of negative frequency-dependent selection, likely owing to predation, but changes in other morph frequencies remained unpredictable. Thus, for specific cases, we can forecast short-term changes within populations, but evolution is more difficult to predict when it involves a balance between multiple selective factors and uncertainty in environmental conditions.According to Zach Gompert at Utah State University, one of the authors, the predictability is hardly surprising: brown stick insects would be found on brown plants, and green stick insects would be found on green plants. The reason is that birds can more easily see the out-of-place morphs and eat them. This explains why out-of-place insects would be missing, but says little about the arrival of the camouflaged species. A USU press release says that the team analyzed 25 years’ worth of data to try to figure out if evolution is predictable.“With the green versus green-striped morphs, the cause of selection was simple and well understood facilitation of predictability,” Gompert says. “In contrast, with the melanistic morph, natural selection was more complex and tied to variation in weather and climate, making it harder to predict from past patterns of change.”The scientists compared their results to better known studies, including Darwin’s finches and the scarlet tiger moth, both of which were also not very predictable.“Our findings support previous discoveries and suggest evolution of morph frequencies in these stick insects is indeed a result of selection,” Gompert says. “They also suggest poor predictability of environmental variation and how it affects selection, rather than random evolutionary processes, might be the main limits on predicting evolution.”While we can use the past to predict change, he says, we’re constrained by our lack of knowledge of the future and complex ecological processes that contribute to change.c. Brett Miller. Used by permission.It’s hard to characterize any of this data support for evolution being predictable. They’re basically saying, ‘evolution is predictable except when it isn’t.’ Reznick and Travis sum up the results:Evolution is like population dynamics because evolutionary change over time can be governed by multiple factors, the relative influence of which vary over time. Nosil et al. used a series of observational data taken over 25 years on natural populations in combination with experiments to show that in one case, evolution can be predicted very well, but in another, it cannot. More generally, they show that without deep biological knowledge, we cannot understand either past or future, much less predict the future from the past.The problem is not just with stick insects. It extends to all of biology:Questionable predictability is not specific to stick insects. Nosil et al. analyzed data sets for other long-term studies of evolution in various species, including Galapagos finches and the peppered moth, and show that they also offer low temporal predictability. In these cases, the likely cause is also multiple forms of selection the strength of which varies over time.Interesting that they would present finches and peppered moths, both of which are “icons of evolution” featured in the list by Jonathan Wells, yet say they were subject to ‘multiple forms of selection.’ Why not simple ‘natural selection’ that strikes so many evolutionists as intuitively obvious? Now, we find, things are not so obvious after all. It’s complicated to predict even one thing on which natural selection might act:These results show that an iconic example of a simple trait subjected to a single agent of strong selection is actually much more complicated. Similar lessons have been taught by other seemingly simple phenomena. For example, the complex ways in which known agents of selection on the color polymorphism of Cepaea snails meant that “each population is subject to a unique explanation”. This is in stark contrast to studies of microbial, viral, and immune system selection, for which evolution seems to be highly predictable. Why this is the case, when it is not so in organisms such as stick insects and others, is a new challenge for evolutionary biologists.So the environment is unpredictable, selection is unpredictable, and mutations are clearly random. Adding three random factors together does not improve on randomness. After 158 years of Darwinian evolution, what has been accomplished to improve scientific understanding other than to say, “Stuff happens”?We like to periodically back up our claim that Darwinism reduces to the Stuff Happens Law. It explains everything; it explains nothing. This is how a stupid idea can put on invisible royal robes and masquerade as an emperor of understanding. Look at these proofs of the Stuff Happens Law we presented earlier. Don’t you feel wiser knowing them?Why the Stuff Happens Law is ScientificIt is reductive: all events can be reduced to this law.It makes predictions: Stuff will happen.It is universal: Stuff always happens.It is normative, not just descriptive: Given matter in motion, stuff must happen.It is falsifiable: If nothing happens, the law has been disproved.It is practical: If something happens, you know you will find stuff around.Corollaries can be derived from it: e.g., Stuff happens at the worst possible time, Bad stuff happens to good people, Murphy’s Law, etc.Impressed?  Darwin’s laws of nature are about as helpful to the understanding of nature as the Stuff Happens Law. Your science might be healthier with a bit of Cole’s Law (i.e., thinly sliced cabbage). (Visited 606 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

South Africa’s Aids action plan

first_img15 March 2007South Africa is finalising an ambitious plan to spend as much as R44.9-billion on halving the rate of new HIV infections in the country by 2011 and providing treatment, care and support to at least 80% of people living with HIV/Aids and their families.A draft of the new five-year National Strategic Aids Plan was discussed by government, business and civil society leaders at a consultative conference in Johannesburg on Wednesday.The final document is expected to be adopted by the South African National Aids Council, which is headed by Deputy President Phumzile Mlambo-Ngcuka, by the end of March.Significant departureThe new plan – drafted in close co-operation with some of the country’s top scientists, actuaries, clinicians, health economists and activists – marks a significant change in South African government policy on the epidemic.The plan places a new emphasis on treatment and prevention, and makes no mention of the dietary recommendations previously cited by the health ministry as key to fighting Aids.It also spells out clear, quantified targets, and places a high priority on monitoring and evaluation. Business Day reports that a special unit is to be set up in the health department to monitor the implementation of the plan, with a mid-term review scheduled for 2009.“There is a new mood and energy in government,” Dr Nomonde Xundu, the department’s chief director for HIV/Aids, told Business Day.Congress of SA Trade Unions general secretary Zwelinzima Vavi told Wednesday’s gathering that, if supported by business and civil society, the plan would be “the boldest, most comprehensive strategic plan on Aids in the world.”Massive spendingAccording to Business Day, Treasury calculations contained in the draft plan put the costs at almost R45-billion – far exceeding the R14-billion the government has already allocated to Aids programmes over the next three years – with up to 40% of this earmarked for Aids drugs.Xundu indicated to Business Day that the government was likely to increase its funding, but would also look to the private sector and foreign donors for assistance.Speaking at Wednesday’s conference, Xundu emphasised that prevention remained key to South Africa’s fight against HIV/Aids.“The intention of the plan is to ensure that the large majority of South Africans who are HIV-negative remain negative,” she said, adding that there was a strong focus on reducing the number of new infections among people in the 15- to 24-year age group.Young people’s choices“The future course of the HIV/Aids epidemic [in South Africa] hinges, in many respects, on the behaviour young people adopt and the contextual factors that affect those choices,” Xundu said.The plan also aims to reduce the HIV infection rate among children under the age of five by expanding the prevention of mother-to-child transmission programme and providing antiretroviral therapy for pregnant women.On treatment, the aim is to increase the reach of the country’s antiretroviral treatment programme from the current estimated one-quarter of HIV-positive people to at least 80% of people living with HIV/Aids as well as their families.In order to lessen the impact of Aids on familes and communities, the plan also aims to expand community-home-based care and palliative care programmes, as well as social safety network programmes for orphans and vulnerable children.‘Formidable partnership’ needed“Nothing less than a formidable partnership between government and civil society can assist us to achieve our goal of reversing the tide of this pandemic,” Mlambo-Ngcuka said on the release of the first working draft of the plan on World Aids Day in December.“Too many people have been infected and too many have died, but if we work together, Aids can be beaten.”According to that draft of the document, HIV/Aids is one of the main challenges facing South Africa, which had an estimated 5.54-million people – 18.8% of the adult population – living with HIV in 2005.“Although the rate of the increase in HIV prevalence has in past five years slowed down, the country is still to experience reversal of the trends,” the document stated. “There are still too many people living with HIV, too many still getting infected.”According to the document, the “immediate determinant of the spread of HIV relates to behaviours such as unprotected sexual intercourse, multiple sexual partners and some biological factors such as sexually transmitted infections.”However, the “fundamental drivers” of the epidemic in South Africa “are the more deep-rooted institutional problems of poverty, underdevelopment and the low status of women, including gender-based violence, in society.”SouthAfrica.info reporter Want to use this article in your publication or on your website?See: Using SAinfo materiallast_img read more

From Liliesleaf to Robben Island

first_imgThe farmhouse at Liliesleaf, in a policephoto taken during the raid.(Image: Liliesleaf Trust) Denis Goldberg in the 1960s.(Image: Historical Papers, University ofthe Witwatersrand) Denis Goldberg is now retired, and livesin Cape Town.(Image: Historical Papers, University ofthe Witwatersrand) Nelson Mandela in the 1960s.(Image: Historical Papers, University ofthe Witwatersrand) Nelson Mandela at a 46664 Arctic concertin 2005. The campaign gets its name fromMandela’s prison number, 46664, andraises funds for and awareness ofHIV/Aids.(Image: 4664 Arctic) A police mug shot of Bob Hepple.(Image: Historical Papers, University ofthe Witwatersrand) Ahmed Kathrada on the cover of hisautobiography, Memoirs. Walter Sisulu in the 1960s.(Image: Historical Papers, University ofthe Witwatersrand) A police mug shot of Andrew Mlangeni.(Image: Historical Papers, University ofthe Witwatersrand) A police mug shot of Elias Motsoaledi.(Image: Historical Papers, University ofthe Witwatersrand) A police mug shot of Rusty Bernstein.(Image: Historical Papers, University ofthe Witwatersrand) An aerial view of Liliesleaf farm, takenduring the police raid.(Image: Liliesleaf Trust) Police inside the farmhouse during theraid.(Image: Liliesleaf Trust) A radio transmitter found in one of theoutbuildings during the raid was used forthe first broadcast of the ANC’s RadioFreedom.(Image: Liliesleaf Trust)Lucille DavieOn hearing they had received life sentences, Denis Goldberg shouted: “Life! Life is wonderful!”On that day, 12 July 1964, the Rivonia trialists had expected the death penalty. Instead, Judge Quartus de Wet handed down four life sentences to eight of them.“All rationality aside, and for all our preparedness to die for freedom in South Africa, we started smiling in disbelief, at first, and complete relief as it sunk in that when the judge said he would not impose the maximum penalty, even though it would be an appropriate sentence,” says Goldberg 44 years later. “By the time he had finished speaking we were openly laughing. In the end most of us got four life sentences, but in the end, you can only serve one of them!”They would live, but that life would include up to 27 years in jail. They would not see their children grow up, nor would they see their wives struggling to hold things together, dealing with harassment by the security police and imprisonment themselves, sometimes with their children.Eight of the 10 trialists were sentenced to life, while two – Lionel “Rusty” Bernstein and James Kantor – were acquitted. Kantor had been arrested a month after the Liliesleaf raid.Of the original eight, only four are still alive: Nelson Mandela, Denis Goldberg, Ahmed Kathrada and Andrew Mlangeni. Govan Mbeki, Walter Sisulu, Elias Motsoaledi and Raymond Mhlaba have died.Mandela is about to turn 90, Goldberg is 74, Kathrada is 78, and Mlangeni is 81 years old.Liliesleaf farmhouse and the outbuildings in Rivonia, where Mandela lived for a time and where the trialists were arrested and, have been restored, and were opened as a museum on 9 June. With two new buildings on the site, the Liberation Centre and the Liliesleaf Resource Centre, it promises to be an exciting addition to South Africa’s museums.Arrest at LiliesleafIn 1961 the South African Communist Party (SACP) bought Liliesleaf farm, some 25km from the Johannesburg city centre, to use as its headquarters. In those days it was a quiet 28-acre smallholding far outside the city.Goldberg, a civil engineer, describes Liliesleaf as having an “exhilarating atmosphere”.“We ate, slept, dreamed, worked at how to make a revolution,” he says. “That is what we did. That is why it was exhilarating. Buying a kombi, buying a farm, moving house, sorting out weapons manufacture, where to get the things needed, how to buy them, how to transport them, how to train people, endless problems to solve.“Sorting out getting passbooks signed without giving away where we were was a problem.”Mandela lived there in disguise, as a gardener and cook under the name of David Motsamayi. A the former president recalls in his autobiography, Long Walk to Freedom: “The loveliest times at the farm were when I was visited by my wife and family.” He says they were times of more privacy than they ever had at their tiny home in Orlando West, Soweto. “The children could run about and play, and we were secure, however briefly, in this idyllic bubble.”But it was not to last.The top leadership of the African National Congress (ANC) – key alliance partners of the SACP – were arrested at Liliesleaf on 11 July 1963. The apartheid government were smug. They had seized and put away for life the top echelons of the liberation movement, who they had caught hatching Operation Mayibuye, the plan to switch to violence to overthrow apartheid.When the police swooped on the farmhouse they arrested Sisulu, Mbeki, Kathrada, Goldberg, Bernstein, Mhlaba and Bob Hepple. Arthur Goldreich, who was ostensibly the owner of Liliesleaf, drove into the farm shortly afterwards, and was arrested along with the others. Goldreich made a dramatic escape from prison, together with Harold Wolpe, Mosie Moola and Abdulhay Jassat, crossing the border shortly afterwards.Mandela was already on Robben Island, serving a five-year sentence for inciting workers to strike, and for leaving the country without a passport.Mlangeni and Motsoaledi had been arrested on 24 June, and were charged together with the other Rivonia trialists.Hepple acted as lawyer for Mandela in 1962, also representing Sisulu and other ANC and Pan Africanist Congress leaders. He too managed to escape over the border before the trial.Today going under the title of Professor Sir Bob Hepple, retired Emeritus Master of Clare College and Emeritus Professor of Law at the University of Cambridge, he is currently judge of the United Nations Administrative Tribunal, sitting in New York and Geneva. He recounts the events on the afternoon of the arrest.At about 3.15pm, 15 minutes into the meeting, a van was heard coming down the drive.“Govan Mbeki went to the window. He said ‘It’s a dry-cleaning van. I’ve never seen it before.’ Rusty Bernstein went to the window and exclaimed: ‘My God, I saw that van outside the police station on my way here!’“I moved to the open door and saw the panel of the van which read ‘Trade Steam Pressers’. I could see a man wearing a white coat, hat and glasses on the front seat. I pulled the door closed. A few moments later I heard dogs barking. Rusty shouted: ‘It’s the cops; they’re heading here.’“Govan had collected up the Operation Mayibuye document and some other papers and I saw him putting them in the chimney of the small stove in the room. The back window was open, and I helped Govan, Walter Sisulu and Kathy (Kathrada) to jump out of it. There was a second or two as I moved back near the door, with Rusty next to me and Ray Mhlaba sitting next to the window.“The door burst open. Detective Sergeant Kennedy, whom I had cross-examined in a political trial earlier that year, rushed in: ‘Stay where you are. You’re all under arrest.’“He walked up to me with an excited sneer: ‘You’re Advocate Hepple, aren’t you?’Hepple was chair of the youth section of the Congress of Democrats, which was part of the anti-apartheid alliance in the 1950s. He was a member of the secretariat which serviced the central political leadership of the ANC.Hepple says that he had been anxious driving to Liliesleaf, or Lil’s place, as it was called, from his chambers in Johannesburg. “My anxieties led me to stop more than once to ensure that I was not being followed. I took a secondary road to avoid passing the Rivonia police station.”He’d had a visit from a “mysterious man” who had appeared unannounced at his chambers that morning, with a message from leaders in Natal leadership for the central underground leadership. “Ever since Mandela’s arrest there had been suspicions about a possible police spy and lax security in Natal. I feigned ignorance and told him to come back the next day. I intended to check his credentials at our meeting at Lil’s place that afternoon.”The leadership were worried about the police discovering Liliesleaf farm, where they had been secretly meeting and living for the past two years. In fact a new property had been bought, a smallholding called Travallyn in Krugersdorp, and Goldberg had moved into it along with Sisulu, Mbeki, Mhlaba and Wilton Mkwayi. It was to become the new ANC headquarters but the next meeting did not take place there.“It could not take place at Travallyn because that would repeat the security failure of bringing people to the place where the leaders of MK [Umkhonto we Sizwe, the ANC’s armed wing] were living in secrecy,” says Goldberg now, referring to Liliesleaf.“They could not at that moment decide on a safe venue, therefore they decided to have one more meeting at Liliesleaf,” he explains. “It was the pressure of the security police surveillance and the house arrests, banning orders, etcetera, that led to the fateful decision.”Solitary confinement and jailAfter arrest Hepple and the other trialists spent almost four months in solitary confinement. Then he was offered freedom from prosecution if he turned state witness. He agreed to do so but, as soon as he was released from jail, escaped across the border with his wife, making his way to England where his young children and parents joined him later.Hepple, like the others, found his jail time hard going.“In the long hours of isolation and boredom, especially as I lay awake at night on the cold stone cell floor, I became obsessed with our predicament. As the days and nights slowly passed I became increasingly confused and created my own world in which reality and fantasy were hard to separate.“Threats and promises made by the police during continuous periods of interrogation became distorted out of all proportion in my mind and my capacity to reason was seriously impaired.“I say this with hindsight, because one of the consequences of sensory deprivation and exhaustion is that one is unable to realise the extent of the changes taking place in normal behaviour.”Mlangeni spent 26 years in prison, with his fellow Rivonia trialists, on Robben Island. He used simple methods to get through the low moments in prison. “I personally would take out the letters I received from my wife and read them over and over again. Look at the photographs I received and that helped me to get myself together again and go back to my studies.”Mlangeni became a politician on his release, and is still a member of parliament.Goldberg says it took discipline and determination to get through his 22-year prison sentence in Pretoria Central Prison. He did not go to Robben Island like the others because he is white.“I believe it was our self-discipline and determination to uphold our dignity, to demand respect, and that the warders act within their own rules, was the key to survival. We found ways of creating our own little world of politics and social contact that enabled us to support each other.“For myself, too, there was the sense of living time day by day. Time was flexible: at Christmas and New Year another year stretched out ahead, and suddenly it seemed the year was over. This was more so for lifers who had no release date.”He describes waking up at 5am, washing in a hand basin in his cell, using the bucket toilet in his cell, then eating a breakfast of watery mealie meal porridge, with a chunk of bread and coffee, which consisted of burnt mealies and chicory.Days were filled with sewing mailbags in the exercise yard, which was freezing in winter, and burning hot in summer.Lunch was “some kind of stew”, supper was powder soup, bread and coffee. “In total each day we were alone in our cells for 16 to 18 hours each day.”Kathrada says in his book, Memoirs: “Nothing could have prepared me for the enormity of losing all choice in such mundane matters as deciding when to wake up and when to sleep, or comprehend that minor joys such as letter-writing and meetings with family and friends would be so severely curtailed and controlled, and that fundamental human rights would become privileges that had to be earned and were always under threat of removal.”Kathrada has been honoured with awards and honorary degrees. While in prison he obtained several degrees. In 1999 he published his Letters from Robben Island, and is currently working on another book. He is retired but consults to the Nelson Mandela Foundation.The islandMandela describes Robben Island as the “harshest, most iron-fisted outpost in the South African penal system”. Being imprisoned at Robben Island was “like going to another country. Its isolation made it not simply another prison, but a world of its own, far removed from the one we had come from.”Mandela says that in Pretoria Central Prison, from where they were flown immediately upon being sentenced, they had felt connected to their families and supporters. But on the island, although they were together as a group, it was little consolation. “My dismay was quickly replaced by a sense that a new and different fight had begun.”The fight involved the Afrikaans-speaking warders demanding a master-servant relationship. “The racial divide on Robben Island was absolute: there were no black warders, and no white prisoners.”To get through the long hours he dreamed about being able “to go to my office in the morning and return to my family in the evening, to be able to pop out and buy some toothpaste at the pharmacy, to visit old friends in the evening”, he says in Long Walk to Freedom.To help him get through his prison sentence Mandela cultivated a vegetable garden. “I had a garden, which I looked after and when the tomatoes were ready, the warders would be very friendly and come and get some tomatoes from the garden,” he recounts with a mischievous smile in a 2006 interview.It was to be a long, hard 18 years on the island, before being moved to Pollsmoor Prison, then Victor Verster Prison, just outside Cape Town, for nine more years, before being released in February 1990.The world on releaseGoldberg says that the world he entered in 1985 was very different from the one he left in 1964.“The world was different after 22 years. Colours were brighter, everything moved faster. I flew in a jumbo jet. I wasn’t sure of how to deal with the outside world.”Goldberg lived in England after his release, representing the ANC in exile, and continuing his anti-apartheid activities. He settled in Cape Town in 2002, where he become special adviser to the Department of Water Affairs and Forestry. He is now retired.Kathrada’s release from prison was marked by “life-changing news” in the form of a simple question: What is a fax?“We had read and heard about this strange new contraption, but none of us had ever seen a fax machine or message, and we simply could not grasp the concept of a sheet of paper being transmitted by telephone, and an exact replica arriving within minutes thousands of kilometres or several continents away.”He was inundated by family and well-wishers when he arrived at his brother’s house in Lenasia, Johannesburg.“Except for a few indelible memories, most of that first day has always been a blank,” he says in Memoirs. “My most precious recollections are of my little grand-nieces and nephews, clambering all over me, clasping their little arms around my neck, holding my hands, hugging and kissing this strange man they had never seen, but had learned to love in absentia.“After 26 years on my own, no other welcome could have meant as much as this spontaneous display of unconditional love and immediate acceptance.”His first television interview brought another surprise discovery. He was confronted with “a cylindrical, black, hairy object that was pushed into my face. I learned very quickly, that day, that this was a ‘boom’, and that I was expected to speak into it.”Mandela had been equally surprised when first confronted with a boom when he walked out of Victor Verster Prison, thinking it a “newfangled weapon” developed while he was in prison.Mandela arrived on Robben Island in the prime of life – he was 44 years old. He left prison as a 71-year-old man.He walked out of Victor Verster Prison on 11 February 1990 to thousands of assembled people, hundreds of photographers, television cameras and journalists. “When I was among the crowd I raised my right fist, and there was a roar,” he says in Long Walk to Freedom. “I had not been able to do that for 27 years and it gave me a surge of strength and joy.”His first night of freedom was spent at Archbishop Emeritus Desmond Tutu’s house in Cape Town. “We were led inside the house, where more family and friends met us but, for me, the most wonderful moment was when I was told that I had a telephone call from Stockholm. I knew immediately who it was. Oliver Tambo’s voice was weak but unmistakable, and to hear him after all those years filled me with great joy.”Mandela and Tambo had been comrades since their student days at Fort Hare University, had set up a legal practice together, and founded the ANC Youth League.Mandela says that in his 27 years in prison, he held “a life-long conversation with him in my head”, and that when Tambo died in 1993, he felt like the “loneliest man in the world”.Mandela was busy after his release. “I began a tour of Africa, which included many countries. During the first six months after my release, I spent more time abroad than at home,” he recounts. “Nearly everywhere I went there were great enthusiastic crowds so that even if I felt weary, the people buoyed me. In Dar es Salaam I was met by a crowd estimated at half a million.”It was reported that a million people greeted him on his ticker tape parade in New York.Mandela is now retired, enjoying his grandchildren and great grandchildren. He will turn 90 on 18 July.Useful linksNelson Mandela FoundationNelson Mandela: reflections on prison lifeRivonia Trial documentsLiliesleaf TrustRobben Island MuseumSouth African History Onlinelast_img read more