‘In the time of the Lord Buddha Vipassi the life-span was eighty thousand years; in the time of the Lord Buddha Sikhi seventy thousand; in the time of the Lord Buddha Vessabhu sixty thousand; in the time of the Lord Buddha Kakusandhy forty thousand; in the time of the Lord Buddha Konagamana thirty thousand; in the time of the Lord Buddha Kassapa it was twenty thousand years. In my time the life-span is short, limited and quick to pass; it is seldom that anybody lives to be a hundred.
From Abhidhamma Teachings:
There is no definite limit: In the four planes of woe the life-span is highly variable, depending on the potency of the evil kamma that produces rebirth there. Thus in the hells some undergo torment only for a few days and then pass on to re birth elsewhere, while other must endure torment for millions of years. In the human realm, too, the life-span can vary from minutes to over a hundred years. Further, according to Buddhist cosmology, the average span of human life also varies over time, ranging between a minimum of ten years and a maximum of many thousands of years.
[An aeon (kappa): The Buddhist texts speak of three kinds of aeons - an interim aeon, an incalculable aeon, and a great aeon. An interim aeon (antarakappa) is the period of time required for the life-span of human beings to rise from ten years to the maximum of many thousands of years, and then fall back to ten years. Twenty such interim aeons equal one incalculable aeon (asankheyyakappa), and four incalculable aeons constitute one great aeon (mahakappa). The length of a great aeon is said by the Buddha to be longer than the time it would take for a man to wear away a mountain of solid granite one yojana (about 7 miles) high and wide by stroking it once every hundred years with a silk cloth.]
The sources for the above material: