What if it isn't a dog-eat-dog world? What if caring for a dog or for a mom with Alzheimer's   makes you stronger and allows you to live longer? Researchers at the University of California, Berkeley are challenging our long-held belief that humans are born to be selfish. Darwin's theory of evolution by natural selection was misunderstood by his male followers, the researchers say. Rather than "every man for himself", Darwin believed that humans are successful as a species precisely because of our educational, selfless and sympathetic characteristics. Why has it taken so long for Darwin's central revelation  to be properly understood? "We've had too many men in social science," Berkeley psychology professor Dacher Keltner told me in an interview. "Female scientists acknowledge that caring for people is part of human nature according to the research, which shows the human ability to care exists in our brains and nerve systems." In my bookPassages in Caregiving, I urge women who take the whole responsibility for taking care of an elderly parent or a sick relative to build a "Circle of Care". Reach out to your brothers and sisters, friends, neighbors and community volunteers to help you care, because no one can perform this overwhelming role alone. You will be as shocked as I to learn how the most selfless caregivers are rewarded with longer life. Sympathy is not a woman's word. In fact it makes all of us stronger under stress and more highly respected by our peers. For so long we have repeated the false saying "Nice guys finish last". But the 40 richest Americans committed to doing good by donating half their fortunes are _ . So here is my new explanation:Nice guys die last. Why does the author mention the 40 richest Americans' commitment in this passage?
To argue against offering sympathy. To use it as an example to support his opinion. To show their generosity to society. To call on people to learn from them.