How to Do Good Science

Richard Feynman (1918–1988) was a very smart American physicist who's words are often quoted ... for good reason.

Here's one quotation where he describes how good scientists should behave. It's a point I make in my class on scientific controversies and it's worth emphasizing because so many modern scientists ignore it.

Feynman is specifically referrring to "cargo cult science" but his advice applies to a lot of of modern biology as well.

There is one feature I notice that is generally missing in "cargo cult science." It's a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty — a kind of leaning over backwards. For example, if you're doing an experiment, you should report everything that you think might make it invalid — not only what you think is right about it; other causes that could possibly explain your results; and things you thought of that you've eliminated by some other experiment, and how they worked — to make sure the other fellow can tell they have been eliminated.

Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can — if you know anything at all wrong, or possibly wrong — to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition.

In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgment in one particular direction or another.

Richard Feynman, "Cargo Cult Science" in Surely You're Joking, Mr. Feynman!

Think about Feynman's words next time you read a paper on the importance of alternative splicing, the disappearance of junk DNA, or anything about evolutionary psychology.

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Splicing Error Rate May Be Close to 1%

Alex Ling alerted me to an important paper in last month's issue of PLoS Genetics. Pickrell et al. (2010) looked at low abundance RNAs in order to determine how many transcripts showed evidence of possible splicing errors. They found a lot of "alternative" spliced transcripts where the new splice junction was not conserved in other species and was used rarely. They attribute this to splicing errors. Their calculation suggests that the splicing apparatus makes a mistake 0.7% of the time.

This has profound implication for the interpretation of alternative splicing data. If Pickerell et al. are correct—and they aren't the only ones to raise this issue—then claims about alternative splicing being a common phenomenon are wrong. At the very least, those claims are controversial and every time you see such a claim in the scientific literature it should be accompanied by a statement about possible artifacts due to splicing errors. If you don't see that mentioned in the paper then you know you aren't dealing with a real scientist.

Here's the abstract and the author summary ..

Abstract

While the majority of multiexonic human genes show some evidence of alternative splicing, it is unclear what fraction of observed splice forms is functionally relevant. In this study, we examine the extent of alternative splicing in human cells using deep RNA sequencing and de novo identification of splice junctions. We demonstrate the existence of a large class of low abundance isoforms, encompassing approximately 150,000 previously unannotated splice junctions in our data. Newly-identified splice sites show little evidence of evolutionary conservation, suggesting that the majority are due to erroneous splice site choice. We show that sequence motifs involved in the recognition of exons are enriched in the vicinity of unconserved splice sites. We estimate that the average intron has a splicing error rate of approximately 0.7% and show that introns in highly expressed genes are spliced more accurately, likely due to their shorter length. These results implicate noisy splicing as an important property of genome evolution.

Author Summary

Most human genes are split into pieces, such that the protein-coding parts (exons) are separated in the genome by large tracts of non-coding DNA (introns) that must be transcribed and spliced out to create a functional transcript. Variation in splicing reactions can create multiple transcripts from the same gene, yet the function for many of these alternative transcripts is unknown. In this study, we show that many of these transcripts are due to splicing errors which are not preserved over evolutionary time. We estimate that the error rate in the splicing of an intron is about 0.7% and demonstrate that there are two major types of splicing error: errors in the recognition of exons and errors in the precise choice of splice site. These results raise the possibility that variation in levels of alternative splicing across species may in part be to variation in splicing error rate.

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Pickrell, J.K., Pai, A.A., and Gilad, Y., Pritchard, J.P. (2010) Noisy Splicing Drives mRNA Isoform Diversity in Human Cells. PLoS Genet 6(12): e1001236. doi:10.1371/journal.pgen.1001236

Extraordinary Claims about Human Genes

Sandra Porter of Discovering Biology in a Digital World has recently attended a talk by Chris Mason of Cornell University. According to Sandra, Chris Mason made the following claims based on his analysis of RNAs from various tissues (human? mammal?). [Next Generation Sequencing adds thousands of new genes]

1. A large fraction of the existing genome annotation is wrong.
2. We have far more than 30,000 genes, perhaps as many as 88,000.
3. About ten thousand genes use over 6 different sites for polyadenylation.
4. 98% of all genes are alternatively spliced.
5. Several thousand genes are transcribed from the "anti-sense"strand.
6. Lots of genes don't code for proteins. In fact, most genes don't code for proteins.

I bet that every one of those claims is wrong.

There's a saying about extraordinary claims—they require extraordinary evidence. In this case, I'm pretty sure the "evidence" is the detection of low abundance transcripts using highly sensitive sequencing technology. Anyone who's ever learned about DNA binding proteins knows about non-specific binding and they know that spurious transcription is inevitable. In order to overthrow our view of the number of genes and how they behave, you will have to convince me that you've ruled out accidental spurious transcription (junk RNA).

I think it's somewhat disingenuous to be giving a talk where you claim we have 88,000 genes and 98% of them are alternatively spliced. (The term "alternative splicing" implies biological significance and not just splicing errors.)

In order to evaluate transcriptome data we need to know the abundance of the transcript. It's not sufficient to simply report that such-and-such region of the genome was transcribed. Researchers have got to report the average number of transcripts per cell in the tissue they are analyzing. I'm betting that if we saw that data we would instantly recognize that the so-called new "genes" are producing less than one transcript per cell. If that's the case it can't be biologically significant in a large mammalian cell.

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How Similar Are Humans and Chimpanzees?

 
When it comes to comparing DNA sequences of individual genes, the human and chimp versions are almost identical in sequence. They differ by only 1-2%. That result gave rise to the oft-quoted similarity of 98-99%.

But that's not the whole story. Outside of the genes there's a large amount of DNA that's less similar. We know this because we now have the sequences of both the human and chimp genomes. Furthermore, there are sequences present in the human genome that are absent in the chimp genome and vice versa. If you look at the whole genomes, the overall similarity is about 95% or so depending on how you do the calculation.

Creationists make a big deal about this. They claim that the newest data proves that evolutionists are wrong and chimps aren't necessarily our cousins. The latest debate is between Fazale Rana on the Reasons to Believe (RTB) website and Dennis Venema on the BioLogos website. The important scientific point is about the actual similarity and how is it calculated?

Fortunately for us, Todd Wood of the Center for Origins Research at Bryan College in Dayton, Tennessee, USA is on the case. Todd belongs to a young-Earth creation study group [BSG] but don't let that fool you. He's doing a pretty good job of sorting out the facts in the case.

RTB and the chimp genome Part 1
RTB and the chimp genome Part 2
RTB and the chimp genome Part 3
RTB and the chimp genome Part 4
RTB and the chimp genome Part 5

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Photo Credit: chimpanzee.net

A Defense of the "Theistic Evolution" Version of Creationism

 
Conor Cunningham¹ has just published a defense of Christianity against the attack of Darwinism. I've ordered his book, Darwin's Pious Idea: Why the Ultra-Darwinists and Creationists Both Get it Wrong, and I look forward to commenting on it in future posts.

Meanwhile, here's an excerpt from his BBC series Did Darwin Kill God? You can see right away that there's going to be problem with someone who equates Darwin with modern evolutionary theory. It means that Cunningham lacks scientific credibility making his arguments mostly moot.

There might be a problem with his theology as well but that's not something I'm very interested in. Perhaps some theist can answer a question? If Genesis has always been taken metaphorically and not literally by the Christian church, then what about the rest of the Bible? Specifically, are Christian supposed to take the stories of Jesus as metaphor and not fact? Is the death and resurrection of Jesus something that never actually happened? Is it just a metaphor? What the official Christian view of this?

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Conor Cunningham is a lecturer in theology and religious studies at the University of Nottingham in the United Kingdom.

Iconic Delusions

 
I don't have much time for blogging these days 'cause I'm in the middle of writing a textbook—trying to be as accurate as possible.

Watch Paul Nelson making comments about the authors of biology textbooks. He sounds very sincere. I think he actually believes that biology textbook authors are deliberately lying. Poor deluded Paul Nelson. That's why we call them IDiots.

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A Test for True Christians

 
Denyse O'Leary doesn't think Theodosius Dobzhansky was a true Christian. She's angry at all those so-called "Christians" who accept evolution because, in her mind, science and Christianity are incompatible [If you are a Darwinist, can you be a Christian if people just say so ... ?].

What do you do about all those fake Christians who believe in theistic evolution? You develop a litmus test, of course.

... if you ask me whether someone is a Christian, I say, "Let him recite the Apostle's Creed and affirm that he believes it and renounces contrary doctrines."

Sounds like a plan. I'll quote the English Language Liturgical Consultation (ELLC) version of the Apostle's Creed and we can discuss whether believing it is compatible with science as a way of knowing. Doesn't look like it to me. Denyse is right!

I believe in God, the Father almighty,
   creator of heaven and earth.
I believe in Jesus Christ, God's only Son, our Lord,
   who was conceived by the Holy Spirit,
   born of the Virgin Mary,
   suffered under Pontius Pilate,
   was crucified, died, and was buried;
   he descended into hell.
   On the third day he rose again;
   he ascended into heaven,
   he is seated at the right hand of the Father,
   and he will come to judge the living and the dead.
I believe in the Holy Spirit,
   the holy catholic Church,
   the communion of saints,
   the forgiveness of sins,
   the resurrection of the body,
   and the life everlasting. Amen.

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Sign a Petition on CIHR Funding

 
Are you a Canadian researcher who cares about the dismal CIHR funding situation?

Sign the petition at: The CIHR Individual Grants Program. It may not do much good but at least you'll have 700+ friends (latest count).

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The Cause of Speciation

 
Jerry Coyne is an expert on speciation. That's why it's always informative to read his latest thoughts on the problem. In spite of what many people might believe, the main cause of reproductive isolation—the actual speciation event according to the biological species concept—is due to accident, not adaptation. It's just one more example of the importance of random genetic drift in evolution.

Here's how Coyne puts it in his latest posting [“Reinforcement” and the origin of species].

Genetic barriers aren’t thought to arise for the purpose of keeping species distinct. Rather, they are usually thought to be evolutionary accidents: geographically isolated populations diverge genetically under natural selection or other evolutionary forces like genetic drift, and that divergence leads to the evolution of genetic barriers (mate discrimination, the sterility of hybrids, ecological differences, etc.) as byproducts of evolutionary change. For example, populations could adapt to different environments (one dry, one wet, for example), leading to them becoming genetically different. When these populations meet each other again, this genetic divergence could result in hybrids that don’t develop properly because the parental genomes are sufficiently diverged that they can’t cooperate in building a single individual.

I wish more people would assimilate this message. It seems to be the overwhelming consensus among the experts in speciation but the average scientist still has an adaptationist view of speciation (and of evolution in general).

Speaking of adaptationists, Coyne also likes the idea that some examples of reproductive isolation can be reinforced by natural selection. You can read about those cases on his blog.

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Let Oprah know that Kim Tinkham died of cancer

 
Kim Tinkham died of cancer today. Orac wants you to Let Oprah know that Kim Tinkham died of cancer. I've already sent my message to Oprah. Why don't you send one?

Watch the video. Oprah sends very mixed messages. On the one hand she advises following the advice of doctors but at the same time she supports The Secret.

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DNA, Phosphorus, and Arsenic

Most of you know that DNA strands have a sugar-phosphate background. The bases in each strand are covalently linked to each other by phosphodiester linkages between the 5′ and 3′ carbon atoms of the deoxyribose sugar.

Recently there has been a claim by NASA-funded scientists that a certain bacterium can replace those phosphates with arsenic. Close examination of the Science paper has revealed that, at most, a few percent of the phosphorus atoms are replaced and even that amount is challenged. It has become abundantly clear from reading the paper that the bacteria absolutely required phosphorus and sufficient quantities were present in the media as contaminants.

I've already linked to Rosie Redfield's critiques of the paper and the press conference. Now I want to add Carl Zimmer's take on the whole affair—the title tells all: "This Paper Should Not Have Been Published".

Carl raises an issue that has cropped up in many of the comments sections of various blogs. Is criticizing a scientific paper appropriate outside of the peer-reviewed scientific literature? Is it ethical to cast doubt on the integrity of scientists when questioning the quality of their science?

Felisa Wolfe-Simon¹ is the lead author of the study and she was the main spokesperson in the video below. Carl Zimmer asked her if she wanted to respond to the criticism of her paper and here's what she said, according to the Slate article,

"Any discourse will have to be peer-reviewed in the same manner as our paper was, and go through a vetting process so that all discussion is properly moderated," wrote Felisa Wolfe-Simon of the NASA Astrobiology Institute. "The items you are presenting do not represent the proper way to engage in a scientific discourse and we will not respond in this manner."

Carl asked some other scientists about this and the best quote comes from Jonathan Eisen,

But Jonathan Eisen of UC-Davis doesn't let the scientists off so easily. "If they say they will not address the responses except in journals, that is absurd," he said. "They carried out science by press release and press conference. Whether they were right or not in their claims, they are now hypocritical if they say that the only response should be in the scientific literature."

My own impression of this fiasco is that the scientific authors of the paper can be accused of bad science and the lead author, Felisa Wolfe-Simon, is guilty of grossly misrepresenting her work at the press conference. There really can't be any excuse for that behavior if you want to call yourself a scientist. Those who think this is impolite and unethical are dead wrong. It's an absolute requirement of good science that we point out to the general public when scientists are behaving badly, otherwise we lose all credibility.

As you watch this video keep in mind that the bacteria absolutely require phosphate in the media in order to grow and that only a few phosphorus atoms, at most, are replaced by arsenic in DNA. If you think that's what Felisa Wolfe-Simon is telling you then you need to work hard on your listening comprehension skills.

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1. The name of the bacterial strain is GFAJ-1. Rumor has it that this stands for "Get Felissa a Job." I wonder how that's working out? Do you think the job offers are pouring in?

John Lennon (1940 - 1980)

 
John Lennon died on Dec. 8, 1980 when he was shot four times in the back by Mark David Chapman. His ashes were scattered by Yoko Ono in Central Park in New York at the site of the Strawberry Fields Memorial.

That was thirty years ago today. A whole new generation has grown up since then and I fear we are in great danger of forgetting what Lennon and The Beatles did to help change our culture for the better.

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The Value of Blogs

Many people have questioned the significance of blogs and bloggers. Some think that science blogs have no useful purpose and that they are undermining the peer review process of publication in scientific journals. Science journalists resent the fact that amateur writers can throw up something on a blog and claim that it's contributing to science education.

Over the years I've come to appreciate that science blogs do at least one thing that's new—they provide instant commentary on science news and that helps to serve as authoritative fact-checking. Science blogs monitor science journalism in the same way that political blogs monitor FOX news and the New York Times.

This role has been illustrated in spades over the past few days as we monitor the response to the NASA hype over bacteria that grow in the presence of arsenic. The weaknesses of the Science paper are now well-known thanks to many science bloggers. In the past, this kind of analysis would have had to wait for the publication of an appropriate critique in a scientific journal and that was very unlikely to happen for a number of very good reasons. Thus, in the past shoddy, over-hyped work got a free pass and science journalists who fell for the hype never even realized that they had been duped.

Read David Dobbs on Wired for a thoughtful analysis of the episode and the lesson we need to learn [Is That Arsenic-Loving Bug — Formerly an Alien — a Dog?]. It's interesting that even Nature News got sucked into promoting the hype. This shows that even journalists at the premier science journals are not very skeptical.

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Arsenic and Bacteria

The blogosphere is not happy with the recent announcement by NASA of bacteria that are able to "thrive and reproduce using the toxic chemical arsenic." [NASA-Funded Research Discovers Life Built With Toxic Chemical]

This finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond Earth. The research is published in this week's edition of Science Express.

I read the paper (Wolfe-Simon et al., 2010) and I can assure you that nothing in that paper is going into my biochemistry textbook. I predict that a year from now we'll have forgotten about this discovery. I'm not even sure it's going to be confirmed but, if it is, the result is pretty trivial.

For a start, even the title of the paper is misleading. The title says "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus" but all of the data show that there was phosphorus in the media and that the bacteria used it for growth and reproduction. This selected strain of bacteria incorporated more arsenic than non-selected species but it by no means did it replace all phosphate with arsenic. Only a few percent (at most) of the phosphorus atoms in DNA, for example, were replaced by arsenic.

The purpose of this posting it to alert you to a fantastic article by microbiologist Rosie Redfield at the University of British Columbia. I strongly urge that everyone read her take-down of the science paper [Arsenic-associated bacteria (NASA's claims)]. The problem is not just that a bad paper was published in Science—it's that the paper was so heavily promoted in the media. We've got to do better when it comes to educating the general public about science.

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Wolfe-Simon, F., Blum, J.S., Kulp, T.R., Gordon, G.W., Hoeft, S.E., Pett-Ridge, J., Stolz, J.F., Webb, S.M., Weber, P.K., Davies, P.C.W., Anbar, A.D., and Oremland, R.S. (2010) A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus. Science Published Online 2 December 2010 [DOI: 10.1126/science.1197258]

Carnival of Evolution #30

 


The 30th version of Carnival of Evolution has been posted on The Scientific Life (Bob O'Hara).

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