“Everyone says, ‘Oh, we’re at the end of an era,’ but the era isn’t going to end,” Mary Lewis tells PEOPLE of the famed ethologist and conservationist

NEED TO KNOW

Goodall, 91, died this week of natural causes in Los Angeles while on a speaking tour
She was slated to speak at UCLA on Friday, Oct. 3, as part of her tour
Assistant Mary Lewis says she was working with Goodall on a document just hours before Goodall’s death was announced

Jane Goodall’s longtime personal assistant says the late ethologist and conservationist was working until nearly the very end of her life — and that work will only continue to benefit the world.

“Everyone says, ‘Oh, we’re at the end of an era,’ but the era isn’t going to end,” says Mary Lewis, Goodall’s personal assistant of 30 years.

Goodall, 91, died of natural causes in Los Angeles while on a speaking tour, her namesake institute announced on Wednesday, Oct. 1,

Lewis, who also serves as vice president at the Jane Goodall Institute, tells PEOPLE that the reaction to the iconic animal welfare advocate’s death — most recognized for her decades of study on wild chimpanzees in Tanzania and outspokenness on conservation and nature — has been remarkable.

“It’s absolutely extraordinary,” Lewis says of the tributes that included Prince Harry and Hollywood stars like Leonardo DiCaprio and Natalie Portman.

But the reaction goes far beyond the star-studded, Lewis adds: “We’ve got 26 Jane Goodall Institutes around the world, and every single one of them is just in overdrive from the local community reaching out.”

And it’s those “talented people” that now realize it is up to them to further Goodall’s legacy.

Goodall, who traveled about 300 days a year for her work, was slated to speak at UCLA on Friday, Oct. 3, as part of her tour. Days after that, she was scheduled to speak at George Washington University in Washington, D.C., on Tuesday, Oct. 7.

On Tuesday, Sept. 30, just hours before Goodall’s death was announced, Lewis says she was working with her on a document up until 10:30 p.m.

“I was actually in bed and I saw this email flash across my phone,” Lewis says, “and I thought, ‘Oh, I’ll send a message saying, Jane, I’ve got to get up at 5 a.m.. I’ll get to you tomorrow night.’ Then I thought, ‘She’s terribly busy.’ So I went and got my computer and sat in bed and started editing.”

Lewis says that Goodall, who is survived by her son, Hugo, and three grandchildren — with whom she tried to Zoom every Sunday, “wherever she was in the world” — was “driven” but she was beginning to feel “finite.” Still, she carried on.

“It was almost as if she had to give every last breath telling people that it was possible to make a difference and that they do matter and that every single daily activity has an impact,” she says. “It’s up to each one of us the kind of impact we have on our planet and our communities.”