If you read the essay, then you'll have seen the graphs in the essay: the histograms of body size. He gave the shape of the curve we would expect if there was some factor - any factor - causing a tendency to larger body size. He then compared this to the curve that we see when we look at the real-world data and explained how they're different, implying that there isn't a tendency to larger body size.Read the book,no help, and neither is any links you can provide, but it may be comforting to justify your atheist agenda.
Like you Stephan Jay Gould has and atheist agenda like you, and his book is Ontological Philosophical approach and the conclusions ARE NOT SCIENCE as Methodological Naturalism is neutral to any such conclusions and cannot by definition falsify the existence nor non existence of God nor whether the nature of our existence is Divinely Created or not,
If you think he made an error in his analysis, then tell me what you think that error is. What you don't get to do is dismiss the data just because you think the person presenting it to you is biased.