How Science Decodes The Past

 

Sometimes religious fundamentalists question the historical nature of science in areas like evolutionary biology, cosmology and geology - claiming that if observations can't be performed in a lab under straightforward test/refute conditions in the present day then the conclusions cannot be justifiably asserted as fact. They say absurd things like: "The fossil record has too many gaps for evolution to be a valid hypothesis" and "We haven't been around long enough to confirm that the earth is older than 6,000 years."

Not only is this wrong, it misunderstands the nature of science, not just how all correct physical theories lock into one consistent, comprehensive inter-connected body of evidence, but how we do, in fact, make predictions about history by predicting what we'll go on to discover about the past.

I'll give you 3 examples of this - one each based on biology, geology and genetics.

1) Evolutionary biologists repeatedly make predictions about transitional forms between different species in their evolutionary lineage. Then subsequent transitional fossils are unearthed in what is a very sparse historical collection, demonstrating the accuracy of those predictions.

2) As well as being able to observe the shape of continents from on high*, geological evidence from plate tectonics and studies of continental drift strongly support the prediction that continents were once connected as a single landmass, known as Pangaea. Similar rock formations, fossils, and even climatic zones across continents that are now separated give clear indications of this once-united supercontinent. Studying the composition of continental edges, and strata similarity has shown how different continents were once fused.

3) Biologists predicted a common ancestor between humans and other apes, and chromosomal studies later went on to show the prediction was correct when they observed that chromosomes in the great apes fused together at some point in the human lineage (Chromosome 2). Here's how we know this. Chromosomes have characteristics called telomeres (the end part) and centromeres (the central part). If fusion occurred between great apes and humans in the past, then one of the human centromeres would include fused telomeres, demonstrating end to end fusion of two ancestral chromosomes. Geneticists have found that this is precisely the case. The presence of a vestigial centromere (remnants of a second centromere in chromosome 2) and vestigial telomeres (remnant telomere sequences in the middle of the chromosome) give present day evidence of ancestral ape chromosomes that fused to give rise to the human chromosome - evidence that can be tested in a lab right before our eyes, and evidence that demonstrates that there is common ancestry between humans and other apes.

(Number 3, by the way, is one of the all time great discoveries - and incidentally one of the many pieces of genetic evidence that nailed the final coffin in creationists’ attempt to deny common ancestry).

One cannot help note with some amusement that, when it suits them, religious fundamentalists employ precisely the same scientific methods as above and steadfastly champion that method when it suits them. For example, they are quite supportive of the science of gravity, electromagnetism and thermodynamics when they are driving their car or enjoying household goods and services that were manufactured using those essential scientific tools.

Even in their reading of scripture they employ the methods they sometimes like to conveniently disparage. For example, in the field of philology, papryologists continued to predict that if any ancient scrolls were found, the discovery would show that books like the Old Testament book of Isaiah will be shown to have been copied faithful to the original. When The Dead Sea Scrolls were found, they contained the oldest extant copy of Isaiah, which showed a strong likeness, with only minor variations typical of ancient manuscript transmission.

The upshot is, historical science is able to inform us about the past, as well as engendering predictions, and it does this precisely because history (to us) isn't a static passage of time that stays unchanged – it is a dynamic story to which we are continually adding our own fuller picture by learning new things and finding further pieces of the conceptual jigsaw. 

* For example, look at an atlas and observe how neatly the eastern coast of South America fits into the western coast of Africa and how the eastern coast of North America fits against the western coastline of Europe.