Old Tools

 
Eva has posted some photos of old lab equipment and tools [Old Tools]. Check them out to see if you recognize anything.

Here's another contribution. This one is pretty easy but starting tomorrow they're going to get much harder. (Click to embiggen.)

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Signals of Positive Selection in Humans?

Signals of recent positive selection in a worldwide sample of human populations is the title of a paper that has just been published in Genome Research (Pickrell et al. 2009).

These workers looked for signs of positive selection using techniques similar to those employed by Hawks et al. in their 2007 paper. That 2007 paper serves as one of the important bits of evidence in the recently published book, The 10,000 Year Explosion.

The idea is to pick out regions of the genome that have linked clusters of polymorphisms (SNPs = single nucleotide polymorphisms). These cluster are called haplotypes and they indicate that a region of the genome has not undergone much recombination in the recent past, because recombination tends to shuffle polymorphisms. One way this linkage could be preserved is when a part of the genome is under positive selection so its increase in frequency is rapid. This is called a selective sweep.

Pickrell et al. (2009) examined a database of 657,143 SNPs called the Human Genome Diversity-CEPH Panel (HGDP). These polymorphisms come from a global sample of 53 populations. The Hawks et al. (2007) paper examined the HapMap database of 3.1 million SNPs from three populations.

Pickrell et al. (2009) also detect a large number of regions that are candidates for positive selection. Their sites overlap those of the earlier study—about half of their sites were also identified by Hawks et al. (2007).

A number of candidates for positive selection are discussed in the paper but the authors note that many of the potential sites are not near any genes that have been well-characterized. It's important to look at individual cases in order to get a feel for the data, especially since the possibility of false positives is a concern.

Specific Examples

Here are a few of the single genes that were identified in one or more groups (e.g. Bantu, Europeans, native American etc.) They are from the top ten strongest signals so they presumably represent some of the best cases for selection.

Heat Shock Transcription Factor 2 (HSF2): This is one of two genes for the major heat shock transcription factor. The heat shock genes are highly conserved and so is their regulation. It's very unlikely that a mutation in the native North American population would be beneficial relative to the allele in all other populations.

succinate-CoA ligase, GDP-forming, β-subunit (SUCLG2) This is the gene for succinyl-CoA synthetase, one of the enzymes of the Krebbs cycle. The data suggest that an allele of this gene was positively selected in the population of Oceania (Pacific Ocean). This doesn't seem very likely.

oxoacyl-ACP synthase, mitochondrial (OXSM) This is the mitochondrial version of a β-ketoacyl synthetase, a standard enzyme required for fatty acid synthesis. An allele shows signs of positive selection in Eurasian populations but not in any other population. It doesn't seem likely that there's an allele conferring a beneficial effect that hasn't already become fixed in mammals over 100 million years ago.

mannosidase, alpha, class 2A, member 1 (MAN2A1) This is a mannosidase located in the Golgi. It's required for one of the last stages in the oligosaccharide maturation pathway—a pathway that's found in all eukaryotes. Pickrell et al. (2009) suggest that an allele of this gene has been selected in the pygmy and Bantu populations. Again, it isn't likely that a standard metabolic gene would be selected in this way.

False Positives?

The patterns of potential selective sweeps strongly suggest local and/or regional sweeps. Since this is the pattern you might expect from random genetic drift, it raises a question about false positives. The authors of the 2009 paper say, ...

Further exploration of the geographic patterns in these data and their implications is warranted, but from the point of view of identifying candidate loci for functional verification, the fact that putatively selected loci often conform to the geographic patterns characteristic of neutral loci is somewhat worrying. This suggests that distinguishing true cases of selection from the tails of the neutral distribution may be more difficult than sometimes assumed, and raises the possibility that many loci identified as being under selection in genome scans of this kind may be false positives. Reports of ubiquitous strong (s = 1-5%) positive selection in the human genome (Hawks et al. 2007) may be considerably overstated. [My emphasis-LAM]

It should come as no surprise that John Hawks disagrees. He has posted a rebuttal on his blog at: Overstating the obvious.

It's an interesting debate but let's not lose sight of the most important point—it is a scientific debate. The case for massive amounts of accelerated human evolution has not been proven in spite of what you might read in The 10,000 Year Explosion and in articles in the popular press.

UPDATE: See Razib's posting: Signals of recent positive selection in a worldwide sample of human populations...maybe

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Hawks, J., Wang, E.T., Cochran, G.M., Harpending, H.C., and Moyzis, R.K. (2007) Recent acceleration of human adaptive evolution. Proc. Natl. Acad. Sci. (USA) 104:20753-20758. Epub 2007 [PubMed] [DOI:10.1073/pnas.0707650104]

Pickrell, J.K., Coop, G., Novembre, J., Kudaravalli, S., Li, J.Z., Absher, D., Srinivasan, B.S., Barsh, G.S., Myers, R.M., Feldman, M.W., and Pritchard, J.K. (2009) Signals of recent positive selection in a worldwide sample of human populations. Genome Research 23 published in advance March 23, 2009 [DOI: 10.1101/gr.087577.108]

Old Tools

 
Eva has posted some photos of old lab equipment and tools [Old Tools]. Check them out to see if you recognize anything.

Here's another contribution. How many readers know what this is and what it was used for in prehistoric times? (Click to embiggen.)

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Fox News host apologizes

 
From the CTV website: Fox News host apologizes in face of Canadian outrage. [See the video at: Here's What Fox News Thinks of Canada's Military.]

The host of a Fox News program has apologized for a segment on the Canadian military that Defence Minister Peter MacKay called "disgusting" and "crass."

A group of pundits on "Red Eye with Greg Gutfeld," which airs weekdays at 3 a.m. on Fox News, each took turns trashing Canada and its military during an episode that aired on March 17.

...

Gutfeld issued an apology Monday afternoon saying, "I realize that my words may have been misunderstood. It was not my intent to disrespect the brave men, women and families of the Canadian military, and for that I apologize."

But the host also seemed to defend his program, adding "Red Eye is a satirical take on the news, in which all topics are addressed in a lighthearted, humorous and ridiculous manner."

I wonder if they've ever treated 9/11 in a "lighthearted, humorous and ridiculous" manner? What about the USA? Have they ever mocked their own country on this show?

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Monday's Molecule #113

 
Identify this molecule and briefly describe its function. You must supply the common name and one of the the formal IUPAC names.

I'm looking for the Nobel Laureate who discovered this molecule.

The first person to identify the molecule and the Nobel Laureate wins a free lunch at the Faculty Club. Previous winners are ineligible for one month from the time they first won the prize.

There are seven ineligible candidates for this week's reward: Guy Plunket III from the University of Wisconsin, Deb McKay of Toronto, Maria Altshuler of the University of Toronto, David Schuller of Cornell University, Adam Santoro of the University of Toronto, Dima Klenchin from the university of Wisconsin, and Alex Ling from the University of Toronto.

Dima has offered to donate a free lunch to a deserving undergraduate so I'm going to continue to award an additional free lunch to the first undergraduate student who can accept it. Please indicate in your email message whether you are an undergraduate and whether you can make it for lunch.

THEME:

Nobel Laureates
Send your guess to Sandwalk (sandwalk (at) bioinfo.med.utoronto.ca) and I'll pick the first email message that correctly identifies the molecule and names the Nobel Laureate(s). Note that I'm not going to repeat Nobel Prizes so you might want to check the list of previous Sandwalk postings by clicking on the link in the theme box.

Correct responses will be posted tomorrow. I reserve the right to select multiple winners if several people get it right.

Comments will be blocked for 24 hours.

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Dropping Courses

 
Chad Orzel of Uncertain Principles has started a discussion about when students should be allowed to drop courses [Academic Poll: Drop It Like It's Hot?].

Why not visit his blog and share your thoughts? I think this is an important issue. Universities may need to make changes.

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Astrology in The Toronto Star

 
I read The Toronto Star every day but I missed this article published last Friday [The vernal equinox: Science and mysticism].

Staff reporter Nick Aveling thought it would be fun to contrast the words of a scientist (Astronomer Randy Attwood) and an astrologer (Michael Barwick). The title of the article implies that this might be an attempt at humor but I'm not sure.

What are the implications of today's equinox?

Attwood: As the earth goes around the sun it appears that the overhead sun seems to be creeping towards the north. For the next three months it will continue to creep north until the first day of summer, when it's at its farthest point north. As the sun gets higher that means it's able to concentrate more heat on the ground.

Barwick: Somebody who's born at 0 degrees Aries – that's a particularly strong Aries person ... William Shatner, Captain Kirk, has kind of the ultimate Aries energy in a way: going forth, boldly going where no one has gone before, pioneering, being in command, leading intuitively. This is Aries.

Phil Plait of Bad Astronomy didn't think it was funny: Canada slips further into goofiness. Neither did any of the people who posted comments on the newspaper's website.

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Old Tools

 
Eva has posted some photos of old lab equipment and tools [Old Tools]. Check them out to see if you recognize anything.

Here's my contribution. How many readers know what this is and what it was used for in prehistoric times? (Click to embiggen.)

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Gene Genie #44

 
The 44th edition of Gene Genie has been posted at Mary Meets Dolly [Gene Genie #44].

My first Gene Genie! For my Catholic readers, Gene Genie is the "blog carnival of genes and genetic conditions." (No rubbing of ancient oil lamp necessary.) I hope I shall do it justice.

The beautiful logo was created by Ricardo at My Biotech Life.

The purpose of this carnival is to highlight the genetics of one particular species, Homo sapiens.

Here are all the previous editions .....

1. Scienceroll
2. Sciencesque
3. Genetics and Health
4. Sandwalk
5. Neurophilosophy
6. Scienceroll
7. Gene Sherpa
8. Eye on DNA
9. DNA Direct Talk
10. Genomicron
11. Med Journal Watch
12. My Biotech Life
13. The Genetic Genealogist
14. MicrobiologyBytes
15. Cancer Genetics
16. Neurophilosophy
17. The Gene Sherpa
18. Eye on DNA
19. Scienceroll
20. Bitesize Bio
21. BabyLab
22. Sandwalk
23. Scienceroll
24. biomarker-driven mental health 2.0
25. The Gene Sherpa
26. Sciencebase
27. DNA Direct Talk
28. Greg Laden’s Blog
29. My Biotech Life
30. Gene Expression
31. Adaptive Complexity
32. Highlight Health
33. Neurophilosophy
34. ScienceRoll
35. Microbiology Bytes
36. Human Genetic Disordrs
37. The Genetic Genealogist
38. ScienceRoll
39. Genetics & Health
40. Human Genetics Disorders
41. ScienceRoll
42. Genetic Future
43. Pharmamotion
44. Mary Meets Dolly

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SEED Reviews The 10,000 Year Explosion

The latest issue of SEED praises US President Obama's emphasis on science and offers a list of ideas "for revising the role of science in America." The number one recommendation is "Make Scientific Literacy a National Priority."

What's needed is better ways of fostering critical thinking and imagination not only in the nation's schools but among its citizenry.

Scientific literacy is not just about being able to weigh in on scientific debates of the day by parsing climate change or understanding the difference between a theory and a guess. The ability to empirically test one's ideas about the world and discard beliefs in light of new evidence is fundamental to the ideals of a just and democratic society; it brings people to the table to debate issues reasonably and with minimum rhetoric.

Good advice, although I wish they'd mentioned the importance of skepticism along with critical thinking. Scientifically literate citizens should not blindly accept every new breakthrough that appears in the scientific literature.

We must rely on good science journalism to inform the general public. Good science journalists will analyze and distill the latest scientific information and help put it in context. They will explain things that are controversial, but exciting, and avoid being swept up by the inevitable rhetoric that accompanies every new discovery.

T.J. Kelleher is a senior editor at SEED. In this same issue, Kelleher reviews The 10,000 Year Explosion a book by Gregory Cochran and Henry Harpending. Let's see whether the review is an example of critical thinking.

This is a trade book, not a scientific publication. The main thesis of the book is that humans are evolving rapidly. This thesis is supported by several lines of evidence.

1. A number of just-so stories from anthropology [see Examples of Accelerated Human Evolution]. Some of them are reasonable, many aren't.
2. A paper published in Dec. 2007 claiming there are thousands of human genes being selected in various populations (Hawks et al. 2007). To the best of my knowledge this analysis has not been independently replicated in the scientific literature and the technology is not without critics.
3. A paper by Hawks et al. (2008) claiming that human adaptive evolution has recently accelerated by acquiring genes from Neanderthals.
4. A claim that within the past 1,000 years the IQ of Ashkanazi Jews has increased relative to the general European population because medieval Ashkanazi Jews engaged in occupations that required high intelligence (Cochran et al. 2006). [See Race and Intelligence, Evolution in the Ashkenazi Jewish Population.]

All this makes for a very interesting book and an idea that's worth serious consideration. It will be interesting to discover, over the next few years, whether there are thousands of genes under positive selection, whether there are only hundreds and the rest are being influenced by random genetic drift, or whether the genetic analysis is subject to artifacts.

Let's see what T.J. Kelleher thinks of all this. Here's the first two paragraphs of the review.

"The 10,000 Year Explosion" would be important even if it were only about population genetics and evolutionary biology, but Gregory Cochran and Henry Harpending, a physicist turned biologist and a biological anthropologist, respectively, at the University of Utah, have written something more. This book is a manifesto for and an example of a new kind of history, a biological history and not just of the prehistoric era. Covering broad ground over human history and prehistory, the authors argue for the singular importance of genes in human history, not just as markers but also as makers.

The first four of the book's seven chapters serve as something of a preamble to the final three. Cochran and Harpending first present the evidence for recent, accelerated human evolution after the invention of agriculture. In its own right that argument is a fairly revolutionary proposition, bit one with clear data, both skeletal and genetic, to back it up: investigations of the human genome undertaken as part of the International Hap Map Project and elsewhere have clearly demonstrated that selection has been ongoing and has accelerated over time. This has been a landmark finding in human biology, and Cochran and Harpending, building on their own work and that of others, including John Hawks of the University of Wisconsin-Madison, convincingly tie the advent of architecture—and the stresses resulting from the new diets. new modes of habitation, new animal neighbors, and new modes of living that agriculture made possible—to this accelerated evolution. It is work destined to launch a thousand careers.[My emphasis-LAM]

Is this an example of critical thinking? Is this the best way to enhance scientific literacy?

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Cochran, G., Hardy, J., and Harpending, H. (2006) Natural history of Ashkenazi intelligence. J. Biosoc. Sci. 38:659-93.

Hawks, J., Cochran, G., Harpending, H.C., and Lahn, B.T. (2008) A genetic legacy from archaic Homo. Trends Genet. 24:19-23. Epub 2007 Dec 3. [PubMed] [DOI: 10.1016/j.tig.2007.10.003 ]

Hawks, J., Wang, E.T., Cochran, G.M., Harpending, H.C., and Moyzis, R.K. (2007) Recent acceleration of human adaptive evolution. Proc. Natl. Acad. Sci. (USA) 104:20753-20758. Epub 2007 [PubMed] [DOI:10.1073/pnas.0707650104]

New Scientist Sheds its Last Ounce of Credibility

Many of us were upset last month when New Scientists published some old news about the early tree of life and sensationalized it on their cover [Darwin Was Wrong?]. They claimed that "Darwin Was Wrong" when, in fact, Charles Darwin didn't even know about molecular evolution or the relationships of bacterial species.

The New Scientist editors admitted that the cover was designed to sell magazines and they seemed to be aware of the problem [Explaining the New Scientist Cover].

They even published a critical letter from Daniel Dennett, Richard Dawkins, Jerry Coyne, and PZ Myers [Blunt Talk from Four Evolutionists].

New Scientists has now begun an ad campaign to attract new subscribers and guess which cover they choose? Jerry Coyne and PZ Myers are advocating a scientific (Coyne) or personal (PZ) boycott of New Scientist. I'm conflicted about that. In spite of its recent errors, New Scientist is far superior to SEED and Discover as a science magazine. If we really want to punish the worst of the popular science magazines then SEED is a much better target.¹

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1. The monthly column by PZ Myers in SEED is the exception, not the rule.

Here's What Fox News Thinks of Canada's Military

 
The ignorance in this segment makes me very angry. Can anyone tell me what the US military is protecting Canada from? The Iraqis? Cubans? The people of Granada or Panama? Kosovo? Afghanistan? Lebanon? Maybe the Somalis, or the Vietnamese?

Canada has only been invaded once in its history (1812) and it wasn't by any of those countries.

Does this embarrass any of my American friends, especially those who like to defend the American media?

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[Hat Tip: Canadian Cynic]

What Is This?

 
This is cool (and refreshing). To find out what it is, visit Mentha ×piperita.

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Canada Has Been Saved from George Galloway

 
George Galloway is a Scottish MP who speaks out on behalf of Palestinians and expresses support for Hamas. He was recently invited to Canada to give a speech in Toronto but Canada's Immigration Minister, Jason Kenney, immediately recognized that Canada can't tolerate that. Kenney determined that a member of the British parliament is a threat to our national security and Galloway was banned from entering Canada.

Jennifer Smith is embarrassed by her country's behavior [Jason Kenney's Personal War on Terror]. So am I.

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"Science journalists? Don't make me laugh"

 
"Science journalists? Don't make me laugh" is the title of an article by Ben Goldacre appearing in The Guardian. Goldacre discusses how British health and science journalists covered the recent papers on testing for prostate cancer.

The bottom line is ...

Journalists insist that we need professionals to mediate and explain science. From today's story, their self-belief seems truly laughable.

Note to science journalists; people are beginning to catch on to your scam. Matt Nisbet helped a lot by making it obvious.

I want science journalists to start policing themselves. It's time to take off the blinders and recognize that many science journalists are not very good at accurately reporting about science. The good ones need to speak out instead of issuing motherhood statements about how good they all are.

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