If you are sure this is an Asimov story then it sounds very like The Naked Sun. This is a good match in everything except the location as it is set on the planet Solaris not Mars.
The detective, Elijah Baley, is sent to Solaris to investigate a murder. Compared to Earth, which has become very crowded, the Solarians live lives of luxury with thousands of robot attendants to take care of their every need. They also have lifetimes much longer than Terrans, though I don't think the details are discussed. The impact of the long lives is specifically referred as you describe by Baley when he is reporting back to his boss at the end of the investigation:
“I believe I know the weaknesses of the Solarians, sir.”
“You can answer my question? Good. Go ahead.”
“Their weaknesses, sir, are their robots, their low population, their long lives.”
Minnim stared at Baley without any change of expression. His hands worked in jerky finger-drawn designs along the papers on his desk. He said, “Why do you say that?”
Baley had spent hours organizing his thoughts on the way back from Solaria; had confronted officialdom, in imagination, with balanced, well-reasoned arguments. Now he felt at a loss. He said, “I’m not sure I can put them clearly.”
“No matter. Let me hear. This is first approximation only.”
Baley said, “The Solarians have given up something mankind has had for a million years; something worth more than atomic power, cities, agriculture, tools, fire, everything; because it's something that made everything else possible.”
“I don’t want to guess, Baley. What is it?”
“The tribe, sir. Cooperation between individuals. Solaria has given it up entirely. It is a world of isolated individuals and the planet's only sociologist is delighted that this is so. That sociologist, by the way, never heard of sociomathematics, because he is inventing his own science. There is no one to teach him, no one to help him, no one to think of something he himself might miss.