There is presumably an upper limit to the carrying capacity of humans on earth—of the numbers that agriculture can support—and that number is usually estimated at between 13-15 billion, though some people think the ultimate numbers might be much higher. (2001)
At the core of punctuated equilibria lies an empirical observation: once evolved, species tend to remain remarkably stable, recognizable entities for millions of years. The observation is by no means new, nearly every paleontologist who reviewed Darwin's Origin of Species pointed to his evasion of this salient feature of the fossil record. But stasis was conveniently dropped as a feature of life's history to he reckoned with in evolutionary biology. And stasis had continued to be ignored until Gould and I showed that such stability is a real aspect of life's history which must be confronted-and that, in fact, it posed no fundamental threat to the basic notion of evolution itself. For that was Darwin's problem: to establish the plausibility of the very idea of evolution, Darwin felt that he had to undermine the older (and ultimately biblically based) doctrine of species fixity. Stasis, to Darwin, was an ugly inconvenience.
Time Frames: The Rethinking of Darwinian Evolution and the Theory of Punctuated Equilibria, Simon & Schuster: New York NY, 1985, pp.188-189
Eldredge and Gould and their many colleagues tend to codify an incredible ignorance of where the real action is in evolution, as they limit the domain of interest to animals... very tardy on the evolutionary scene, and they give us little real insight into the major sources of evolution's creativity.
Lynn_MargulisThe Third Culture: Beyond the Scientific Revolution ed. John Brockman (1995)
Although Haldane accepted the earlier and incorrect paleontological interpretation of the fossil record of Gryphaea, in his overall belief that the pace of evolution was rapid and seemingly discontinuous, rather than slow and continuous, he anticipated, at least in part and by three decades, the model of punctuated equilibria, which was proposed by... Niles Eldredge and Stephen Jay Gould.
According to Gould and Eldredge, the reason why so many links are missing is that they simply do not exist. They take the view that biological evolution proceeds in successive stages of "punctuated equilibrium." Living species would remain unchanged for extremely long stretches of time, and then undergo profound changes in relatively short periods. To borrow a term from the quantum theory of atoms, evolution would occur in "quantum jumps." It is very likely that the spark of life appeared during the first such "jump."