If my understanding is correct the contentious point with my proposal is the word consilience, which is unfortunate - because it is the perfect term for this. 's proposal isn't too bad, but it does not address the problem with the first sentence. In an attempt to drop the consilience term and to remain consistent with Provine's description of the modern synthesis I offer the following to replace the first two sentences in the fourth paragraph (the first uses consilience):
"In the early 20th century, an evolutionary synthesis coupled a new quantitative theory of heredity to Darwinian selection and forged a consilience of knowledge from previously fractured branches of biology. Purposive theories, such as orthogenesis and "progress", became obsolete."
"In the early 20th century, an evolutionary coupled a new quantitative theory of heredity to Darwinian selection and offered a new approach for testing evolutionary theory. This new way of investigating evolution served to unite previously fractured branches of biology and purposive theories, such as orthogenesis and "progress", became obsolete."