You got me there! I actually did look up Milankovitch Cycles on Wikipedia, but only to get the spelling correct. I didn’t read enough to find the quote you listed.
I’ve been going by articles on Ice Age Cycles indicating that the approximate 100,000 year Ice Age repetition rate is third order of the longest Milankovitch cycle, not once per cycle, and also the start of the Ice Age, some 500,000 years ago is unexplained. Maybe Wikipedia has something here. It’s often too Left biased to be meaningful.
According to most geologists, the current pre-Ice Age
era started when Antarctica drifted over the South Pole: It’s ice cap began over 25 million years ago! This pulled a lot of moisture out of the atmosphere and significantly dried out the rest of the Earth. Supposedly, the dryer air meant less jungle or forest that ranged from Europe, across Africa and all the way to East Asia. This was a time when monkeys were evolving into apes and at the time, 25-20 million years ago, ape species were at their highest diversity. As time went on, these forests, due to global cooling and drying, turned into savannas, and some apes became bipedal, perhaps to walk upright and see over the tall grass—couldn’t compete with other ape’s ownership of the remaining forests, so were stuck out in the borderlands and couldn’t climb the much fewer trees to escape predators (total speculation here). By 10-7 million years ago, supposedly these kinds of apes split off from the orangutan/gorilla-chimp line and became hominids.
They also say that when, again due to continental drift, South America connected to North America thru the newly formed Panama isthmus around 2.5 million years ago, and the Tethys ocean -between Asia and East Africa (the area is now Southern Iran thru Turkey and Saudi Arabia) disappeared this cut off the circumglobular oceanic warm current, which cooled the Northern hemisphere so much that the truly big glaciers we think of really started to form over North America and Europe.
So supposedly we’re still in an Ice Age—just a warm interglacial—that started 12,000 years ago. Milankovitch cycles explains how the entire 2.5 million year current Ice Age, of maximum glaciation to interglacials, actually works.