Shirley Kurtz attends Enciende Una Luz, a Mennonite congregation near Harrisonburg, Va..

The lore is as varied as the earth’s peoples. A sampling:

In the beginning there was only darkness, water, and the great god Bumba. One day Bumba, in pain from a stomachache, vomited up the sun. The sun dried up some of the water, leaving land. Still in pain, Bumba vomited up the moon, the stars, and then some animals: the leopard, the crocodile, the turtle, and, finally, some men, one of whom, Yoko Lima was white like Bumba.—Bantu tribe, Central Africa

P’an Ku hatched from a cosmic egg. Half the shell was above him as the sky, the other half below him as the earth. He grew taller each day for 18,000 years, gradually pushing them apart until they reached their appointed places. After all this effort P’an Ku fell to pieces. His limbs became the mountains, his blood the rivers, his breath the wind and his voice the thunder. His two eyes were the sun and the moon. The parasites on his body were mankind.—Taoist monks, China

In the Land Above The Sky a strong wind uprooted this tree. Skywoman, walking by, fell through the hole left by the tree. As she fell a flock of geese broke her fall and she landed on a giant turtle that rose from the waters. This giant turtle grew in shape and size to form the land. There Skywoman gave birth to a daughter whose children propagated the human race.—Iroquois tribes, North America

God separated the light from the darkness, shaped the sky, and drew together the seas to form the land. God caused the land to grow plants and trees, and God pinned the sun, moon, and stars in place, and he created the birds and beasts and last of all a man and a woman in his own image. After six days of toil God took the seventh day to rest.—Hebrew nomads, Middle East

Mix-ups in this last story—the modifications in Genesis chapter 2—deserve note. In the second telling, not until after he fashions the man out of dust does God plant a garden and trees in Eden. And only after God creates the animals and brings them to the man to name does it occur to God that not a one of them will make a proper helper for the man. So God puts the man to sleep and takes out one of his ribs and makes the woman.

A person can only imagine the details. God crouching next to the shallows to pat out some dirt-and-creekwater mud into organs, muscles, corpuscles, a skeletal system, skin, and hair, and then blowing down the windpipe to dry out the pattycake man and start his blood to humming. And, as if in rectification of an oversight, God hacking into the man’s chest and twisting loose a bone, carving it into a wee lady figure, pumping it like a bicycle tire up to size.

Evolutionary theory, too, staggers the mind. Cosmic dust collects into ever larger clumps, one of which becomes the place we now call Earth, layered over with molten rock. The surface cools enough to allow for the presence of water, and chemical reactions lead to molecules complex enough to replicate. The invasion of eukaryotic cells by cyanobacteria allows them to carry out photosynthesis. Single-celled life forms give rise to multi-celled, and in time, sea life proliferates. The land remains uninhabited except for a few feisty bacteria, until a species of algae, predecessor to all plant life today, creeps up some damp embankment. Eventually coastline plants create an environment hospitable enough for sea vertebrates to immigrate.

The charts are right there in any high school or college biology textbook depicting the branching-out of terrestrial vertebrate life: lobe-limbed fish, then amphibians, then reptiles, then mammals (dinosaurs and birds sit on limbs forking off from the mammals’ branch). Farther up that branch, the primates emerge, mammals having binocular vision and opposable digits (thumbs). The thumbs allow greater deftness in grasping objects. Contrary to what is supposed—and feared—by some opponents of evolutionary science, the evidence does not indicate chimpanzees giving rise to humans. Rather, chimps and hominins—the line of primates with homo sapiens as the sole survivor—appear to share the same unknown ancestor.

Still, a shared ancestor? This might be the aspect of evolutionary theory most alarming to religious opponents. It’s what troubled patrons and board members at the Mennonite school in Pennsylvania where my husband got dismissed from his teaching job, back in 1986. No doubt those same people are still suspicious of the science. “We won’t quibble over a literal six-day creation,” said the school board. “And animals and plants evolving, that’s fine. But man? Man was created special, in the image of God.”

How must God look, then? Based on us, God is bipedalian, an upright walker? God possesses the same thick-enameled canine tooth structure that distinguishes hominins from apes, the same close-set eyes affording visual acuity, the non-slanty forehead, the handy thumbs (and thanks to the Y chromosome, a beard)? Is that the deal, then? Or what?

The biology textbooks sort the evidence for evolution into categories. For one, the earth’s age, calculated from rocks by a process known as radiometric dating. Those billions of years were required for evolution to proceed at its snail pace—for the life that exists today to develop. Two, the fossil record. The earth’s sedimentary layers continue to yield specimens showing consistent movement toward more complex life forms. Three, the likeness of structure seen in diverse species, indicating linkage to a common ancestor. For example, bat wings, whale flippers, and cat legs all feature a single bone joined to two bones joined to five, marking a shared heritage; these forelimb variations are the result of natural selection. Occasionally, too, natural selection results in a homologous structure that’s nonfunctional, or vestigial: ostrich wings are built like other birds’ wings but no longer work as wings; the strange appendage at the base of the nascent spine of an 8-week-old human embryo is sometimes classified as a vestigial tail. And a further category of evidence relies on genetic research, studies performed at the molecular level. Deductions about evolutionary relationships can be drawn because the DNA of every organism on earth—animal, plant, and bacteria—codes for the same amino acids.

These different lines of corroboration came up in the biology course my husband taught last spring at Eastern Mennonite University in Harrisonburg, Va. Sitting in on his evolution lecture—I was riding along to classes twice weekly, scrunching into one of those hard student desks—I couldn’t make sense of the chart flashing past on the projection screen matching humans with kangaroos, cows, dogs, rodents.

Since then, I’ve pored over it. Nucleotide substitutions? Every so often a wrong C, A, G, or T base links into a nucleotide joining the chain in a cell’s strand of DNA during replication—the replication process goofs—and one and another and another such substitution, or mutation, can lead to altered physical characteristics in the plant or animal or bacteria, making way for the development of a new species.

Obviously all this takes time, inconceivable stretches of it. The more time crawling by, the more changes. So comparing the same gene in two unlike species can be a way to document when those species diverged. The above study of the cytochrome c gene, showing fewer nucleotide differences between the cow gene and the goat gene compared to the increasing differences when the cow gene is compared to the gene in llamas, pigs, horses, dogs, and humans, suggests that of the species listed, cows are closest cousins with goats. Generally the evidence lines up with previously formulated hypotheses about these species’ development.

Let me say a bit more, yet, about that riverside scene: God alongside the meandering Euphrates (Nile? Omo? Zambezi?), tenderly patting out the mud body. I stayed silent in science class, never once made a peep, though my head was spinning. Ions? Electron shells? Mitochondria, lysosomes, endoplasmic reticulums? Polypeptide chains? Mitosis versus meiosis?

I remained mute, ventured no questions, but I ask now: why the antagonism among religious groups toward claims made by science? Is the prospect of humans’ and nonhumans’ shared lineage too much of an insult? If the “days” in Genesis, the exquisite sequence of events leading up to the mud man and rib lady, can be seen as poetry, why not the Adam-and-Eve part, too?

The ancient version of the story, the textbook version—they’re equally boggling. Even with thumbs, how can we possibly grasp our past, our history, our meaning?