Thousands of people rallied in Australia and New Zealand Saturday in support of science, the first of more than 500 marches globally triggered by concern over the rise of "alternative facts".
The March for Science demonstrations come amid growing anxiety over what many see as a mounting political assault on facts and evidence and fears that research is being excluded from policy-making.
Vocal protesters in Sydney wearing white lab coats called on politicians to support the scientific community, carrying banners reading "without science, it's just fiction" and "we need thinkers not deniers".
Others held up slogans such as, "What do we want? Evidence-based science. When do we want it? After peer review."
The protests came as US Vice President Mike Pence was completing a three-day visit to Australia.
While American organisers have said the marches planned there are non-partisan, they admit the Republican administration under Donald Trump -- who has vowed to slash the research budgets of top US agencies -- "catalysed" the movement.
Fears that science is under political assault in Australia have likewise grown under its current conservative government and demonstrators also turned out in Melbourne, Brisbane, Perth, Adelaide and other cities as well as Wellington and Auckland in New Zealand.
"In this day and age, there's so much fake news and alternate facts going around that it's important to remember that science is what has built the society we know today," Parissa Zand, who was at the Sydney march with her molecular biologist mother, told AFP.
High-school science teacher Byrne La Ginestra said science had been getting a "bum-rap", adding that "we need to... teach people that science isn't a political agenda, it's just facts".
Canberra last year reversed a decision to cut hundreds of jobs from the national science body CSIRO after a public outcry. Others worry that the government is not doing enough to protect the Great Barrier Reef, which is under threat from climate change.
Brazil, Canada, many European nations, Japan, Mexico, Nepal, Nigeria and South Korea are all also planning science marches.