I’m not sure whether this is a more general creationist thing or something specific to Seventh-day Adventists (because I think it comes from an Ellen G White comment rather than from Scripture), but when I was growing up SDA it was a commonplace that Adam (Eve was never mentioned, but presumably was to scale) was on the order of 12 feet (just under 4 m) tall. So, similarly to their long lives, pre-Fall and shortly post-Fall humans were seen as being much, much larger than current humanity.
The thing is, there is a law in biology, derived from physics, called the square-cube law. The reason is pretty simple: strength increases as the square of height, because it is proportional to the cross-sectional area of bones (or their equivalent for things with exoskeletons and so on), while mass increases as the cube (because volume does and assuming relatively constant density).
This means that we can’t simply scale things up and down at will as though on a slider in a video game, because the relative strength to mass ratios change. Doubling the height multiples the bone diameter by 4 but the mass by 8, for example.
That means that the femurs that work for a 6 ft (a bit less than 2 m) man would really struggle to carry the weight of a 12 ft one. Either Adam would be quite frail, or his proportions would have to be quite different from ours.
I’ve never heard of that belief that A&E were giants, even if I’ve heard a lot about many kinds of creationism. It must be pretty localized to SDA circles.
I guess if a YEC is already willing to apply different laws of nature operating 6,000 years ago in the case of the Flood and other matters, it’s not a stretch to think that they’d be OK with either 1) reconfiguring the concept of a “gigantic” Adam and Eve so that they wouldn’t violate these laws (e.g. A&E had different bone density), or 2) believing that physics was entirely different at the time.
By the way, this is a fun paper by physicist Don Page on estimating the height of the tallest organism in our universe based on nothing more than the fundamental constants.
I had remembered reading about the square-cube law as it relates to nephilim and other giants in the Bible. So here is that quote from AIG if it’s of interest:
Furthermore, it should be pointed out that the square-cube law is accurate when applied to building materials, but it doesn’t seem to perfectly relate to biological organisms, although it probably provides some “ballpark” limits. For example, the average house cat is about 30 inches long (head to tail), 9–10 inches tall, and weighs about 11 pounds, while tigers reach 12 feet in length (head to tail), 3 feet in height, and weighs about 500 pounds.35 If we were going to estimate the weight of a 10-foot long, 3-foot tall cat using the square-cube law, based on the dimensions of the average house cat, then the numbers would not match what we see in reality. According to this rule, when we quadruple the length (2.5 feet to 10 feet), then we would need to multiply the weight by 64 (4 x 4 x 4), which means we would expect the weight to be approximately 700 pounds. This is significantly higher than the weight of a tiger of this size.36
This example shows that tigers and house cats do not share the exact same proportions, but this is exactly the point. Both animals belong to the created cat “kind,” and the much larger varieties (lions, tigers, etc.) are not perfectly “scaled up” compared to the smaller varieties. If this were the case with giant humans, then perhaps a 13’6” Og isn’t out of the realm of possibility, but the notion that some biblical giants were 20–30 feet tall or greater is probably a “stretch.”
I’m also the weirdo that created a thread here suggesting that a gigantopithecus tooth could be a human fossil after gigantopithecus had landed in my news feed soon after I had researched more about the nephilim. It would be interesting to see what is proposed for the proportions of the gigantopithecus. I don’t remember getting that far into it.
I do not think it makes sense for Adam and Eve to be taller than the giants described on the Bible or there would be no reason to make such a distinction about the Nephilim. I see no reason also that they couldn’t be taller than humans today, but it’s just extra-biblical speculation and I don’t think it has any importance.
It would be interesting to see what is proposed for the proportions of the gigantopithecus. I don’t remember getting that far into it.