SEATTLE - While Bill Gates spends his billions immunizing children in sub-Saharan Africa, funding scholarships and helping the homeless, his Microsoft co-founder Paul Allen is backing the search for extraterrestrial life.
Allen, to be sure, underwrites tens of millions of dollars in medical research and other mainstream charitable causes.
But his large-scale philanthropy exhibits a flair for the dramatic - even monumental - that promises a more visible and perhaps controversial legacy than his former partner's.
''Interests that really shape his philanthropic identity are now being clearly articulated in the projects he funds. He has fun,'' said Dwight Burlingame of the Center on Philanthropy at Indiana University.
Gates, whose $60 billion fortune generally puts him atop the list of the world's richest individuals, has made his Bill and Melinda Gates Foundation the world's richest, with an endowment of some $22 billion.
Allen's $28 billion fortune usually keeps him among the top three in the world, according to Forbes' rankings. His six Paul G. Allen Foundations made 174 grants this year, the largest a $20 million donation to the Seattle Public Library to buy books and build a children's section.
Other recent eye-catching - or eye-popping - Allen projects include:
- Experience Music Project, an interactive music museum whose wildly inventive, multihued, curved-metal body designed by architect Frank Gehry has drawn the global gaze, if few flat-out raves from Seattle residents. The $240 million museum, which began as a tribute to Seattle-native and Allen guitar hero Jimi Hendrix, is run as a nonprofit foundation.
- The Seattle sculpture garden. Allen last year ponied up the $4 million necessary to finish the purchase of waterfront property where this outdoor extension of the Seattle Art Museum will rise.
- The SETI Institute: Allen earlier this year donated $11.5 million to build an array of telescopes in Mountain View, Calif., that will search for radio waves emanating from distant planets as proof of alien life.
''He has diverse tastes,'' said Allen spokeswoman Susan Pierson-Brown, noting that Allen has backed SETI since its congressional funding was cut.
In making the grant, Allen said, ''For the first time in our history we have the ability to pursue a scientifically and technologically sophisticated search for intelligent life beyond earth. This new telescope will be the world's most powerful instrument for this search.''
The Gates Foundation's work has virtually all been service-oriented, including a $750 million pledge for a global children's vaccination program, and $1 billion for the Gates Millennium Scholars scholarship program.
The common theme in Gates' giving ''really is equity,'' said Gates Foundation spokesman Trevor Neilson. ''Right now we have unprecedented opportunities to improve people's lives. The goal of the foundation is to bring some of those opportunities in terms of health and education to people who might not have them.''
That theme springs naturally from Gates' life experience, Neilson said.
''He has traveled quite extensively and has seen some of these things firsthand, and his father and mother both instilled in him a real global view,'' he said.
''Fundamentally, philanthropy is based on the philanthropist's individual interests. It's what they want to address in terms of the public good,'' said Burlingame, noting that John D. Rockefeller, the Bill Gates of the turn of the last century, devoted much of his fortune to eradicating hookworm.
Allen's philanthropic interests began to take shape when he left Microsoft in 1983 after contracting Hodgkin's disease, which went into remission with extensive treatment.
''To be 30 years old and have that kind of shock - to face your mortality - really makes you feel like you should do some of the things that you haven't done yet,'' Allen says in a new book, ''Inside Out: Microsoft in Our Own Words.''
Most of Allen's grants are made quietly.
''We don't self-promote our giving,'' said Susan Coliton, manager of the Paul G. Allen Foundations. ''Promotion of it and recognition for it is not the driving factor behind the philanthropy.''
The Gates Foundation aggressively publicizes donations, staging large-scale news conferences and pursuing coverage. Neilson dismissed the suggestions of some that Gates' massive giving in recent years is a public-relations response to the government's threatened antitrust breakup of Microsoft, which Gates still heads.
''Bill has said for over 20 years that he would return his wealth to society. That has been something he's maintained and now is in the process of doing,'' Neilson said.
Burlingame noted that Rockefeller offered to make his great fortune a gift to the American people at the time his Standard Oil's operations were under similar government pressure at the turn of the last century.
But in Gates' case, ''I don't think it has anything to do with that,'' he said. ''I think it's more a thing of passage, where he finally got to be 40 years old. With a lot of other younger e-types who made all these millions and billions, they just acquired their wealth much faster than what was the case historically.''
