If phrases like “the conservation of conservatism” or “the production of productivity” leave you scratching your head, you may wear off a few hairs thinking about a paper in PNAS1 on the “evolution of evolvability.” Entitled, “Is evolvability a selectable trait?”, this paper by two scientists at Rice University considers whether the rate of change of evolution can change. (Pause here to think about that.) In other words, can the ability of a population of critters to adapt to its environment quickly be selected by natural selection? Might some critters become sluggish in their ability to change, while others develop flexibility in adapting to changing conditions? Why is anyone even asking this question? It’s not that no one has thought about this before, but the idea has been shrugged off by other evolutionists in the past. How could a population plan ahead to be flexible? For this reason, the authors seem a little defensive writing this paper:Whether the propensity to evolve, or evolvability, can be an object of Darwinian natural selection is a topic of interest. Causality would suggest not because of the apparently anticipatory nature of evolvability. Many within the field of evolutionary biology are uncomfortable with the concept that evolvability is a selectable trait. A growing body of experimental data, however, would be explained if evolvability were a selectable trait. Higher organisms cannot evolve, or adapt, by germ-line mutation to an environmental change within their own lifetime. Does this mean that lineages and individuals cannot be under selection for evolvability?….….Although the use of the term evolvability has only recently come into vogue in the scientific community, investigations into the evolution of adaptation go back several decades. Prominent from a theoretical perspective are works in population genetics and game theory [see 02/10/2004 headline]. Despite the insights that these studies give as to the origin and maintenance of evolvability, evolution of and selection for evolvability remains a contested issue primarily because of the causality principleSo the burden of proof is on them to show that evolvability evolves. Their paper is primarily a mathematical model, similar to computer models of evolution (see 07/04/2004 headline). A model is needed, they say, because of the difficulty of measuring the effect in the wild:Whether evolvability is selectable has been a difficult question to answer, primarily because observations in evolutionary biology tend to be correlative in nature and difficult on which to make mechanistic conclusions. Therefore, we consider here the dynamics of evolvability in a well defined theoretical model of protein evolution. Within this model of protein structure and function, we have a fixed population of proteins, which we take to be 1,000. We have a microscopic selection criterion, which we take to be the folding and binding of a protein to a substrate. And we have a means of inducing constant, random environmental change.They claim the model shows that evolvability is a function of environmental change; the more dynamic the environment, the more evolvable the protein. This, they emphasize, is their important finding. It’s kind of like physics:An analogy with thermodynamics illuminates the issue: How is free energy minimized in a physical system of particles despite the difficulty in defining the entropy of a given configuration of the particles? An ensemble of particle configurations allows the definition of free energy and the approach to thermodynamic equilibrium just as a population of evolving organisms allows the definition of and selection for evolvability.They seem to be viewing individual organisms as molecules, and treating Darwinian selection as a force acting on the ensemble– a form of group selection (see 05/31/2004 headline for opposing view). Is there any evidence in nature for their position? They point to a few possibilities:Many observations within evolutionary biology, heretofore considered evolutionary happenstance or accidents, are explained by selection for evolvability. For example, the vertebrate immune system shows that the variable environment of antigens has provided selective pressure for the use of adaptable codons and low-fidelity polymerases during somatic hypermutation. A similar driving force for biased codon usage as a result of productively high mutation rates is observed in the hemagglutinin protein of influenza A. Selection for evolvability explains the prevalence of transposons among bacteria and recombination among higher organisms.Is this concept useful? The authors feel that “therapeutics also confer selective pressure on the evolvability of pathogens, and that this driving force for antigenic drift should be considered in drug- and vaccine-design efforts.” The believe their model shows that “The rates at which the various events within the hierarchy of evolutionary moves occur are not random or arbitrary but are selected by Darwinian evolution. Sensibly, rapid or extreme environmental change leads to selection for greater evolvability. This selection is not forbidden by causality and is strongest on the largest-scale moves within the mutational hierarchy.” One of their concluding statements summarizes their view into a pithy sound bite: “Not only has life evolved, but life has evolved to evolve.”1David J. Earl and Michael W. Deem, “Evolvability is a selectable trait,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0404656101.It must get boring at the Darwin Party storytelling banquets (see 12/22/2003 commentary), so every once in awhile someone has to come up with a new plot to argue about. To these guys, proteins in a test tube are a microcosm of caribou in the tundra or humans in Manhattan. This paper might suggest a short story or novel on whether New Yorkers are evolving evolvability in response to terrorist attacks. If so, terrorism might be a good thing; it makes the species more adaptable to sudden change. It doesn’t matter whether the model corresponds to reality or not, or can be observed or not, as long as it makes entertaining reading, generates lively discussions and opens new markets for GameBoy.(Visited 12 times, 1 visits today)FacebookTwitterPinterestSave分享0
Citizens everywhere deserve the respectof their governments. They also sharethe responsibility, with their leaders, ofcreating an adequate society. With the continent’s abundance of the sunand wind, solar technology advances inAfrican countries should have become apriority many years ago, said Ramphele.(Images: Southafrica.info)MEDIA CONTACTS• Steve Biko Foundation+27 11 403 0310Valencia Talane“We need a philanthropic movement in this country where each one of us does what we can do.”This was said by distinguished philanthropist, academic and businesswoman Mamphela Ramphele back in 2007, citing, among other concerns, a need for South Africa’s emerging middle class to share more of its wealth in order to help address poverty and inequality in the country.Fast forward to five years later, today – Ramphele has delivered such a movement.The Citizens Movement for Social Change, launched in April, encourages a culture of accountability and proactiveness among citizens, which will see them grow beyond a nation wounded by colonialism and apartheid.Addressing attendees at the launch in Cape Town, Ramphele echoed her words from 2007, saying: “Accountability mechanisms to ensure citizens remain stewards of the democracy and at the centre of governance have not yet been developed.”On the other hand, a change in how leaders view the people on the ground is also necessary to lessen the gap between those who hold the power to govern and those who should be benefiting from the government.In an interview with Business Day earlier this year, Ramphele said one of the flaws of South Africa is that in the transition to democracy “we skipped a step”, forgetting to liberate ourselves from the psyche of an apartheid society, which had thrived on the principles of job reservation and exclusion.“We underestimated the depth of the chasm that we inherited. We thought we could throw money at education and money at other things, but it required much, much more,” she said.“Now the best weapon anyone has to arrest the slide is to become an active citizen and champion of the Constitution, which enshrines social justice.”Lessons from AfricaFrom 2000 to 2004 Ramphele was one of four managing directors at the World Bank, and the focus of her post was human development in Africa.It was a great achievement for her on an individual level; she was the first African to reach a position of such seniority at the global financial institution.“My contribution to the World Bank was to say ‘what is good for people in the US and China is good for people in Africa’, which I think has helped the bank think more holistically in their efforts on development,” she said.However, she reckons, it was a great learning curve for her as well.Speaking to UK-based Ubraintv.com – a digital network that focuses on energy and environmental news – Ramphele shared her views on Africa’s preparedness to start taking care of itself, so to speak.There are parts of Africa that are working, and some that are not, she said.“”Ethiopia, which was in the media for the wrong reasons a few decades ago, is now pioneering the process of reforestation,” she said, referring to the famine that gripped the Horn of Africa country, where varying reports put the number of deaths between 400 000 and 900 000, with many more displaced.“This was achieved by ordinary people whose government had to catch up with the citizens.”She added that the events of the last year or so in the continent’s Arab nations were also a sign of the revolutionary change that can be brought about by citizens.These are ordinary people taking charge of their own issues, demanding that governments meet them halfway in creating governable states that address the needs of the poor.Africa has a unique way of communicating, said Ramphele. Many people in Africa subscribe to a culture of meeting in a circle, with everyone around the circle having a say and contributing towards a solution for the concern of the day. This is known as a kgotla, from the Setswana word meaning “court”.“There is no hierarchy in a circle, so everybody gets a turn to be heard,” she reasoned.This will come in handy, said Ramphele, in the networking and knowledge-sourcing processes that African scientists should be enlisting in order to advance the continent’s chances at fighting climate change.Technology in the fight against climate changeRamphele is of the view that most of postcolonial Africa’s governments ignored the investment in their people and, therefore, the enabling of Africans to innovate.“Despite Africa’s shortcomings in terms of governance, the interconnected world allows us to look at what is happening elsewhere, and determine how we can adapt that to our environment,” she said.“From having looked at the technology the world has to offer, combining it with our natural resources like the sun and wind, we should be able to develop technology that is appropriate for our needs.”Through the work of the Technology Innovation Agency, a government agency of which Ramphele is chairperson, she is able to see benefits of the internet and social media revolution, with young people now able to connect to their peers around the world to share ideas.Ignoring the changes around the globe will, in time, mean that we will fall behind in our efforts to preserve the planet, she said, and when we run out of time, nature could punish us.“The current shift to think beyond economic growth and to embrace an approach towards human development means that at all levels of governance, national, continental and global, we have a set of actors who are well informed.”Nurturing a responsible citizenryThe task ahead, Ramphele argued, is to mobilise citizens to voice their rights and exercise their responsibilities.Without an active citizenry and with enduring poverty and development failures, South Africa is headed down a dangerous path of instability. *Image of Mamphela Ramphele courtesy of Wikipedia
Why Tech Companies Need Simpler Terms of Servic… 8 Best WordPress Hosting Solutions on the Market A Web Developer’s New Best Friend is the AI Wai… Ever logged in to Tumblr on your iPhone or iPad? How about while logged in on a public Wi-Fi connection? If you answered yes to any of the above, you may want to change your Tumblr password ASAP. Tumblr has just made users aware of a serious privacy compromise that enables anybody with the ability to “sniff” traffic on public Wi-Fi networks to view Tumblr users’ passwords in unencrypted plain-text format. The problem arose because the iPad and iPhone apps fail to log users in through a secure server. An official Tumblr announcement urges Tumblr users to change their passwords immediately if they’ve used the app, and to download the newest version of the app as soon as possible:If you’ve been using these apps, you should also update your password on Tumblr and anywhere else you may have been using the same password. It’s also good practice to use different passwords across different services by using an app like 1Password or LastPass. Related Posts lauren orsini Top Reasons to Go With Managed WordPress Hosting Tags:#Password#security#Tumblr Please know that we take your security very seriously and are tremendously sorry for this lapse and inconvenience.According to the Register, a reader found the bug by chance while evaluating the Tumblr apps for suitable use on his employer’s smartphones. It’s a surprisingly enormous security hole for the Yahoo-bought company to overlook. Anybody who has ever accessed Tumblr over public Wi-Fi from a mobile device, whether at an airport, a coffee shop, or a library, is at risk. Fortunately, Tumblr users don’t seem to be reporting any serious consequences. The Tumblr #password and #security tags abound with users spreading the news, but not with sob stories about compromised accounts. Even if a user does find her account has been compromised, it will be hard to peg it on this security breach in particular.
After blockbuster Dabangg Sonakshi Sinha is all set to make a comback in Rowdy Rathore along with Akshay Kumar.Bollywood’s original Khiladi Akshay Kumar returns to what he is best at- action. He will be seen packing some hardcore kicks and punches in Prabhu Deva directed Rowdy Rathore when it releases Friday.Made with a budget of approximately Rs.40 crore, the film is a remake of Telugu film Vikramarkudu. It is co-produced by Sanjay Leela Bhansali and Ronnie Screwvala. The film will be released in 2,300 screens in India and around 400 screens overseas.The film revolves around Shiva (Akshay), who is a small-time conman. He is head-over-heels in love with Priya (Sonakshi Sinha), a pretty girl whom he met at a wedding he wasn’t invited to. The picture perfect world of Shiva turns upside down with the entry of six-year-old girl Neha, who believes he is her father.Shiva also becomes the victim of a series of life threatening attacks by a gang of deadly criminals, who seem to know something he doesn’t. In the quest to save his life and love, Shiva stumbles upon a deadly secret, something which takes him to a small town in Bihar.That town is ruled by a ruthless MLA and the mafia he controls. The inhabitants of the small town find a saviour in Shiva.Akshay is said to have learned combat karate for his role in the film. He is seen sporting a rugged look in the film. The movie bosses had launched an online hunt for Akshay’s look for Rowdy Rathore.The cast and crew of the film had a tough time shooting in Karnataka’s temple town of Hampi. The shoot was disrupted after activists alleged that the makers didn’t use the minimum number of local dancers that they had promised.Sonakshi’s red sari act in the song Chhammak challo chail chabeeli has compelled people to draw comparisons with Kareena Kapoor’s Chhammak chhallo in RA.One. However, the actress brushes it off as mere co-incidence and insists the two songs should not be compared.Filmmakers have been coming up with innovative ways of promoting a film or launching the music and Rowdy Rathore too tried a new trick. The film’s music was launched in a chawl in Mumbai.This will be Sonakshi’s second release after blockbuster Dabangg.After this, Akshay and Sonakshi will appear together in Joker and strike a hattrick with Once Upon A Time Again.Two of the film’s songs have a slew of Southern and Hindi film actors making a special appearance. While Chinta ta chita has Tamil star Vijay, Kareena Kapoor, Rajesh Hamal and Prabhu Deva himself, Aa re pritam pyaare has Maryam Zakaria, Shakti Mohan, Mumaith Khan and Amit Kumar.advertisement