Saturday, September 01, 2012

Friday Journal Club: Variables Associated with Acceptance of Evolution

by Salman Hameed

The start of the semester is close and meetings ate up Friday. So Friday Journal Club is on Saturday. I want to talk a bit about a recent paper by Benjamin Heddy and Louis Nadelson: A Global Perspective of the Variables Associated with Acceptance of Evolution published in the journal Evolution: Education and Outreach.

The paper used published data from 35 countries to look at factors that influence the acceptance of evolution. In particular, they looked at four factors: a) religiosity, b) school life-expectancy, c) science literacy, and d) GDP per capita. They collected information about these variables from various sources, like Gallup polls for Religiosity, PISA (Program for International Student Assessment) for science literacy, etc.

The authors provide a reasonable justification for why each of these variable might be linked with the acceptance of evolution. For example, school-life expectance - defined as the average years of schooling per citizen within a country - may be increase personal knowledge of science, which in itself is correlated with the acceptance of evolution. In case you are wondering, "Pakistan has a school-life expectancy of seven years (CIA 2007), which signifies that on average, a given citizen in Pakistan has attended seven years of school in his/her lifetime. In contrast, the United States has a school-life expectancy of 16 years (CIA 2007), which indicates that the average United States citizen has attended 16 years of schooling."

What I liked about the paper is that the authors are keenly aware of the limitations of their study. For example, the fact that they are using evolution acceptance/rejection data from multiple sources, and the questions in each survey may not properly match-up. Nevertheless, they have tried to get the best possible data and have tried to open up the questions for further research.

So what do they find? Well, here is the main table from their paper that shows the relationship of acceptance of evolution with the above-mentioned four variables:

Don't worry about the specific numbers - but it shows that the acceptance of evolution goes down in countries where self-identified religiosity is higher. On the other hand, the acceptance of evolution goes up with the increase in the three remaining variables. Some of the variables over-lap and interact with each other, nevertheless, the religiosity factor stands out (with the data they have used):
It is apparent from our calculations that our four indicator variables overlap; however, it is also important to note that the largest coefficient of determination associated with these variables was between religiosity and school-life expectancy, r^2=.39. This suggests that about 39% of the variation in religiosity can be explained by school-life expectancy, which still leaves over 60% of unique variation between the variables. Further, the correlations reflect the irreducible nature of these data, as it is unlikely that any indicators of social and economic status are going to be independent. Therefore, we proceed with the recognition that there is some overlap of the data; however, there is also likely to be substantial unique contribution by each of the measures in association with evolution acceptance.
With this caveat in mind, we do see a negative correlation of evolution acceptance with religiosity at country-wide level in a sample of 35 countries. While the list of religions represented in these countries is not exhaustive, there are still a number of Christian and Muslim denominations in their data to make a a general claim about the impact of self-identified religiosity.

But why religion? Here is the speculation from the authors:
We speculate that the mechanism by which religion influences acceptance of evolution is followers’ trust in authority. Religious authorities, both people and doctrine, may convey messages that communicate ideas that contra- dict the theory of evolution, and because of the expectations of trust, the messages are likely to promote followers to embrace rejecting evolution. The conflation of the world- views of religion and science has resulted in tension and the development of positions that equate the two as similar in their epistemologies (Taylor and Ferrari 2011). However, we contend that it would be productive to help citizens realize that evolution and religion do not have to be at conflict and that authorities can come in many forms. Developing and studying such interventions is an excellent direction for future research.
Well...yes - and I more or less agree with their basic conclusion. But then, of course we also have to ask how individuals within different cultures interpret the conflict, and that may lead in some cases to competing epistemologies, and in other cases to a matter of group or social identity. Nevertheless, their findings provide a (very) broad picture of the evolution acceptance landscape, and it is a useful marker to have.

By the way, while reading some of this, I was reminded of my previous life working on star formation in spiral galaxies. My thesis work focused on individual galaxies (about 60 in total) and by the end I knew them quite well (oh - NGC 986 - you are still such a beauty). But then there were surveys of thousands (and now even hundreds of thousands) of galaxies that looked at the broader star formation trends in this group of galaxies. However, the fun part was to know the details of an individual galaxy and then see it falls followed the expected larger trend or not. And those that did not, made up a fascinating sub-sample (it turns out that some in the sub-group were interacting with small galaxies).

I know that people and galaxies are different, but it will be interesting to see if deeper studies of evolution acceptance within individual countries identify sub-groups that buck these global trends. And investigating the reasons for that will be fun.

That is it for this week's journal club. You can find past Irtiqa Friday Journal Clubs here.

Heddy,B.C. and Nadelson,L.S. (2012), A Global Perspective of the Variables Associated with Acceptance of Evolution
Evo Edu Outreach (2012), DOI: 10.1007/s12052-012-0423-0


Naveed said...

The correlations are really interesting. Specifically that the acceptance of evolution theory is predicted more by the length of time in school as opposed to scientific literacy. I thought that was quite a non trivial result.

Is there any followup data to measure the quality of scientific literacy and school work on the acceptance of evolution theory?

Salman Hameed said...

Yes - that is interesting (though there is also a correlation between school life-expectancy and scientific literacy). I can't see a clear reason why that might be the case. Perhaps, it is because of the exposure of a system of knowledge versus the information - but this sounds too contrived to fit the finding. My guess is that this may be due to some data inconsistency issues, and the difference may go away in follow up studies. I don't know about any follow-up studies (and this paper just came out last month). But this is the reason I liked this paper as it suggests ways of further investigations.

Ben Heddy said...

You both make really great points. Naveed and Salman, we have no data as to the quality of science literacy and school work. However, I believe I can find such data and that would be a really interesting follow-up. We just had a follow-up to this manuscript accepted in Evolution: Education and Outreach where we explored similar variables for the United States specifically. If you send me an email I would be happy to forward it to you. (

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