Some activists registered people to vote. Others urged visitors to stamp their cash with political messages. Daniel McDonald was collecting poop.
The UC San Diego researcher was among more than 1,000 scientists, data geeks and everyday people to attend the March for Science at Waterfront Park on Saturday, the second annual drive to celebrate knowledge and connect data to everyday life.
McDonald was staffing a booth promoting American Gut, a self-proclaimed citizen science project that aims to sequence and study millions of donated stools to better understand how individual human microbiomes can save lives.
The scientific director of the American Gut project said research like his is critical, and grants from sources like the National Science Foundation and Environmental Protection Agency are drying up.
"Science generates innovation, which generates new economies," he said.
The 2018 march, which unfolded in hundreds of other cities across the nation on Saturday, was nowhere near as well-attended as the inaugural event a year ago, when 15,000 people paraded through downtown San Diego to support scientific research.
But the organizers, speakers and attendees this year were every bit as passionate about what they see as a need to shield science from political influence and make sure public policies are based on evidence rather than ideology.
They spoke about how science can save lives, create new industries and improve the human condition. They talked about pushing for explanations about arcane and routine questions that can spark innovations that change the world.
"Science is going to be political, but it doesn't have to be partisan," said Mary Canady, one of the march organizers and the co-founder of a newly established nonprofit called San Diego For Science. "We tell people what the important issues are when looking at candidates."
While speakers at the March for Science were largely non-partisan, some marchers carried signs criticizing President Trump because he has called climate change a hoax and threatened to cut funding for research.
"Science is important, not only to science but to the world," said Robbie Todd, a professional photographer from North Park. "To me, science and art go hand in hand because they both work toward proving things. It seems like today science is under attack."
Trump supporters did not appear to attend the march in great numbers.
Emily Knight, a volunteer with the activist group Represent San Diego, attended the march to promote an effort to reduce the influence of money in politics by stamping messages like "This Bill Shall Not Be Used To Bribe Politicians" directly onto dollar bills.
"An average of 875 people will see your bill over its lifetime," Knight told one woman who stopped by the booth. "This is completely legal, but make sure you don't stamp it in the center."