Tag: phylogeny

Evolutionary trees help to convict men who knowingly infected women with HIV

By Ed Yong | November 15, 2010 3:00 pm

HIV_3Dmodel

In 2004, evolution itself served as a witness for the prosecution in the case of the State of Washington versus Anthony Eugene Whitfield. Whitfield contracted HIV in an Oklahoma prison, and first learned about his infection in 1992. After his release in 1995, he had more than a thousand sexual encounters with 17 different women, even fathering children with three of them. He rarely wore a condom, never told any of his partners about his infection and flatly denied it when asked.

However, Whitfield did confess to various people that if he had HIV, he would give it to as many people as possible. He got his wish – five of his 17 partners became HIV-positive. Whitfield was finally arrested in 2004 and convicted on 17 counts of first-degree assault with sexual motivation, among other offences. His total sentence came to 178 years and a month.

To demonstrate Whitfield’s guilt, the prosecution had to show that he had wilfully exposed women to HIV, that his five HIV-positive partners contracted their infections from him. Fortunately, David Hillis from the University of Texas and Michael Metzker from Baylor College of Medicine knew exactly how to do that. They had evolutionary biology on their side.

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CATEGORIZED UNDER: Evolution, Genetics, Select, Viruses

Do new discoveries ever “rewrite evolutionary history”?

By Ed Yong | September 1, 2010 9:00 am

Etch-a-sketchasaur

You can’t go for a month without seeing a claim that some new discovery has rewritten evolutionary history. If headlines are to be believed, phylogeny – the business of drawing family trees between different species – is an etch-a-sketch science. No sooner are family trees drawn before they’re rearranged. It’s easy to rile against these seemingly sensationalist claims, but James Tarver from the University of Bristol has found that the reality is more complex.

Tarver focused on two popular groups of animals – dinosaurs and catarrhines, a group of primates that includes humans, apes and all monkeys from Asia and Africa. Together with Phil Donoghue and Mike Benton, Tarver looked at how the evolutionary trees for these two groups have changed over the last 200 years. They found that the catarrhine tree is far more stable than that of the dinosaurs. For the latter group, claims about new fossils that rewrite evolutionary history (while still arguably hyperbolic) have the ring of truth about them.

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Extra genomes helped plants to survive extinction event that killed dinosaurs

By Ed Yong | March 23, 2009 5:00 pm

Blogging on Peer-Reviewed ResearchSixty-five million years ago, life on Earth was sorely tested. One or more catastrophic events including a massive asteroid strike and increased volcanic activity, created wildfires on a global scale and dust clouds that cut the planet’s surface off from the sun’s vital light. The majority of animal species went extinct including, most famously, the dinosaurs. The fate of the planet’s plants is less familiar, but 60% of those also perished. What separated the survivors from the deceased? How did some species cross this so-called “K/T boundary”?

Jeffrey Fawcett form the Flanders Institute for Biotechnology thinks that the answer lies in their genomes and specifically how many copies they have. Geneticists have found that the majority of plants have duplicated their entire portfolio of genetic material at some point in their evolution. They are called “polyploids” – species with multiple copies of the same genome.

By dating these doublings, Fawcett had found that the most recent of them cluster at a specific point in geological time – 65 million years ago, at the K/T boundary. It suggests that having extra copies of their genomes on hand gave these plants the edge they needed to cope with the dramatic environmental changes that wiped out the dinosaurs and other less well-endowed species.

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Bacteria and languages reveal how people spread through the Pacific

By Ed Yong | January 22, 2009 2:00 pm

Blogging on Peer-Reviewed ResearchThe area collectively known as Austronesia covers half the globe. It stretches from South-East Asia and Taiwan, across New Guinea and New Zealand, to the hundreds of small islands dotted around the Pacific. Today, it is home to about 400 million people.

They are the descendants of early humans who spread throughout the Pacific in prehistoric times. These forebears are long dead but they left several unexpectedly important legacies that are evident in their modern descendants. The languages they used evolved and splintered into over 1,200 tongues spoken by modern Austronesians. The bacteria in their bodies did the same, giving rise to distinct strains in different parts of the region.

Two new studies have used these very different hitchhikers – one cultural and one biological – to piece together the routes of this ancient mass migration. And they have come to the same general conclusion.  

The Austronesian people originated in Taiwan some 5,000 years ago. After a few centuries of settlement, they started a massive pulse of migration, spreading southwards and eastwards. They moved to the Philippines, dispersed across South-East Asia, and spread as far west as Madagascar and as far east as the Micronesian islands. They reached Fiji and other islands in Western Polynesia about 3,000 years ago and there, they paused again. About 1,500 years ago, they started a second big migration pulse that took them east across the Pacific all the way to Easter Island.

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CATEGORIZED UNDER: Bacteria, Language
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