There is no doubt that it is hard to be a discerning consumer of information and arguments. After all, society seems to roughly divide into experts and the uninformed masses. And who are we, the masses, to question the experts?

Certainly one wants to show respect for expertise which may have taken years to acquire. However, in most disciplines we find experts who support very different conclusions. One has only to think about psychology, medicine, biotechnology, economics, or climate science to realize how divided expert opinion can be. Certainly it is good to provide the opportunity for all points of view to have their say. It then soon becomes apparent that worldview has a lot to do with the conclusions taken by any given expert within a field of study.

Now, one cannot accept all the different points of view. It is important to critically evaluate the arguments, even those which claim to represent the majority position, particularly in science, which some in society assume is the arbiter of all ideas that are worthy of support.

It cannot hurt, for example, to find out on what basis scientists draw their conclusions. Does worldview drastically affect the shape of their arguments? An interesting insight into this issue was an interview by Suzan Mazur published in Huffington Post (online May 7, 2015). She interviewed Eugene Koonin, director of the Evolutionary Genomics Group at the National Center for Biotechnology Information in Bethesda, Maryland. This expert declared that when we look for information on origins, all we have to go on is inference (conclusions drawn on the basis of indirect evidence). Suzan Mazur quotes Dr. Koonin as declaring:

Everything we're saying about the past is inference – yet, inference is not a derogatory term. We are every major taxon of animals as the key starting point for the evolution of vertebrates. Very confident about much of this inference … We are confident that all animals had a common ancestor about 700 million years ago, a little less. Although, do we know that? No. And no one is ever going to find that ancestor and experiment on that ancestor. In that sense, we do not know that. Do we have doubts? No. Reasonable evolutionary biologists have no doubts about that.

Obviously those who share Dr. Koonin's views on evolution will agree that the inferences he draws are worthy of acceptance. But the more we look at evolutionary theory the more reason we have to be critical. It is less certain than it seems – its conclusions built on flimsy evidence.

Clueless but confident⤒🔗

Take for example the way evolutionary scientists will compare various living organisms, speculating how one more complex body type might have evolved from another simpler one. Common theories hold that:

• cells without nuclei (prokaryotes) evolved into cells with nuclei (eukaryotes)
• single cell animals (protozoans) evolved into animals made up of many different kinds of cells (metazoans)
• animals without a body cavity (acoelomate) were the ancestors of those today with a body cavity (coelomate)
• those with a body plan divided into many symmetrical parts (radially symmetrical) evolved into those with two sides which are mirror images of each other (bilaterians)

In all these cases there are many theories which take for granted that evolution from the one group to the other occurred, but these theories cannot agree on what exactly the evidence indicates. They agree that it happened, but disagree as to how it happened – in other words, no matter how differently they understand the evidence, they all come to the same final conclusion. That should highlight for us the speculative, and worldview-based, nature of their conclusions.

Take as a further illustration some recent articles on vertebrate origins and evolution. Vertebrates are animals with a backbone – animals without a backbone are called invertebrates. In creatures that have a backbone, their body plan consists of a straight progression from head to tail, or from mouth to anus.

In invertebrates, however, there may not necessarily be a head, and the body shape may be coiled or radiating in many directions: the sky is basically the limit in design choices. Well-known invertebrate body types include corals, jellyfish, clams, octopus, snails, flatworms, sponges, sea cucumbers, and various worm designs.

A series of articles on vertebrate origins and evolution appeared in the April 23, 2015 issue of Nature. In introductory remarks, the editor of this series declares:

…vertebrates have so many special features, from large brains to complex physiologies to unique tissues such as enamel and bone – that their evolution from invertebrates is obscure.

Hmmm. Notice that while there is no clear evidence as to how it might have happened, the editor does not ask whether an evolutionary process took place. He assumes that it did. Authors of the first article similarly begin by declaring:

Biologists have considered nearly Hmmm again. This does not look very promising as a basis for studying vertebrate origins – things are so unclear they don't even know where to start.

Which came first?←⤒🔗

It gets even more interesting. Invertebrates like starfish begin their lives as swimming larvae before they later transition to their adult stage.

Now, the experts are sure that vertebrates evolved from invertebrates but they disagree as to which stage of invertebrates' lives evolution acted on. Some think that initially evolution first acted only on the invertebrate ancestors' swimming larval stages, while others think that it first acted on their adult stage.

The experts who think vertebrates came from evolution acting on the larval swimming stage think the best course of investigation is, therefore, to compare appearances and similarities of various invertebrates' immature swimming stages. They assume that at first, this larval swimming stage was all there was to these organisms. It was only much later that some of them developed sedentary shapes and biology that are much different from the swimming stages and much different from the later development of other swimming stages. For example, there are some swimming larval stages of starfish relatives that later settle down into creatures with bodies divided up into multiples of five equal parts. Another group, the sea squirts, have swimming larvae that later settle down to appear like sedentary vases with a side spout as well as an upper opening.

Now, the swimming larvae from various groups may show a fair number of similarities to one another, even though in their adult forms they look totally different. How such extremely different adult shapes and biologics came to be added onto their life cycle, the experts do not worry about so much.

Meanwhile, other experts assume that the initial state of these organisms was actually like the adults that we see today and they argue that it was the swimming larval stages that only appeared much later. So when these experts try to figure out how invertebrates evolved into vertebrates they only consider the characteristics of the adult stage. How the development of the adult stage was later delayed to accommodate a new totally different swimming larval stage is, again, anybody's guess.

If we came from Worms←⤒🔗

There is another major source of disagreement between experts when considering vertebrate origins. Some support the "annelid theory." Earthworms are annelids. They have a nerve running along the underside of their body (ventral position). However vertebrates have the major nerve running along the top or back body wall (dorsal position). What the experts propose is that the position of the nerve cord was somehow relocated from front of the body to back during the invertebrate-to-vertebrate transition.

The alternative theory is called the acorn worm (enteropneust) theory. The original expert who focused on these marine worms was British geneticist William Bateson in 1886. These very weird looking worms have three body regions: a proboscis, collar, and trunk. Bateson thought these were a good potential ancestor of vertebrates because they have gill slits (considered an important vertebrate characteristic during development). Bateson suggested that these worms already have their nerve cord in the dorsal position, but others declare that these worms have no nerve cord at all, just a nerve net which could potentially evolve into a dorsal nerve cord. It is apparent that what you label a structure determines how significant it will be in arguments about origins.

I could cite many other examples from this series of Nature articles to highlight just how speculative the nature of evolutionary conclusions can be. I'm going to restrain myself, however, to keep this already technical article from getting too technical. What I am trying to highlight here is that conclusions concerning lines of descent toward vertebrates depend upon very indirect arguments. The only conclusion that the experts agree on is the idea that vertebrates developed from some sort of invertebrate ancestor.

Conclusion←⤒🔗

So, remember that one should not feel intimidated by technical discussions. Find out the definitions of the jargon terms and dive into the material. You don't need to understand every part of the discussion to be able to get an overall understanding of the shape and quality of the arguments being made. One article in the vertebrate origins series, for example, included the following caveats in close succession:

• "it seems reasonable to assume"
• "it is likely"
• "may have facilitated"
• "may have allowed"
• "thus was probably"
• "a likely scenario"
• "might have enabled"
• "usually taken to support the contention"
• "may have been fostered by"

Terms like these are clues that the conclusions may be largely speculation. Often, too, commentaries by other experts can help one understand the significance of the material in the technical article.

The take home lesson is that you should not allow yourself to be intimidated by experts who claim to support the consensus (majority) view. There is plenty of room for critical evaluation of these views and for consideration of alternative interpretations. It is evident that careful reading of technical articles can reveal some very interesting shortcomings in evolutionary conclusions even though they are so confidently proclaimed by many authorities in the field. Expert conclusions are often only as good as the values on which they are based. The experts may be attractive personalities, they may sound confident and their arguments may at first sound plausible, but this is no excuse to uncritically accept what they say.