In the summer of 1973, the House Committee on Merchant Marine and Fisheries approved a version of the Endangered Species Act and sent the bill to the floor of Congress. To accompany the measure, the committee—now defunct—produced a report that offered the following analogy. Imagine that a copy of every book in the world had been deposited in one enormous building. Now imagine that a madman was somehow able to enter the building, light a bonfire, and incinerate part of the collection. The response would be outrage. At the very least, the administrators of the building would be censured; probably they would be replaced.

“So it is with mankind,” the report observed. Like it or not, humans had become the administrators of the planet: “we are our brother’s keepers, and we are also keepers of the rest of the house.”

A few weeks after the report was issued, the House approved the bill by a vote of 390–12. The Senate approved its version 92–0. During the signing ceremony for the Endangered Species Act, President Richard Nixon said, “Nothing is more priceless and more worthy of preservation than the rich array of animal life with which our country has been blessed.”

Forty-five years later, there is a madman in the building. In fact, there are several. Last week, the Trump Administration proposed what the Times called “the most sweeping set of changes in decades” to the regulations used to enforce the Act. The changes would weaken protections for endangered species, while making it easier for companies to build roads, pipelines, or mines in crucial habitats. Under current regulations, government agencies are supposed to make decisions about what species need safeguarding “without reference to possible economic or other impacts.” The Administration wants to scratch that phrase. It also wants to scale back protections for threatened species—these are one notch down on the endangerment scale—and to make it easier to delist species that have been classified as endangered.

Greg Sheehan, the acting director of the U.S. Fish and Wildlife Service, an agency within the Department of the Interior, said that the proposed changes were aimed at “providing clarity.” Representative Raúl Grijalva, an Arizona Democrat and the ranking member on the House Natural Resources Committee, by contrast, called them “part of the endless special favors the White House and Department of the Interior are willing to do for their industry friends.”

Also in the past few weeks, congressional Republicans have introduced some two dozen measures and, perhaps more importantly, spending-bill riders aimed at weakening the Act. The version of the Pentagon budget that the House approved last month, for instance, included a provision that would have prohibited the Interior Department from granting protection to the sage grouse, a fantastic bird whose numbers have declined by an estimated ninety per cent since the nineteenth century. (The provision, which the Pentagon objected to, was stripped out a couple of days ago.)

There are, to be sure, plenty of problems with the Endangered Species Act. While it has been instrumental in saving certain iconic species from extinction—such as black-footed ferrets and manatees—it hasn’t altered the basic fact that extinction rates in the United States—and, indeed, everywhere—are now hundreds, perhaps thousands of times higher than they’ve been at most other points in the history of life on Earth. Relatively few species that have been put on the endangered list have recovered to the point where they can justifiably be removed from it. (One that has, happily, is the bald eagle.) Increasingly, the forces pushing species toward the brink are those, like climate change and ocean acidification, that weren’t anticipated when the Act was written.

Meanwhile, despite all the—forgive the pun—grousing by oil and gas interests and their friends in Congress, there’s not much hard evidence that the Act has caused economic losses. Other federal agencies are supposed to consult with the Fish and Wildlife Service to insure that proposed projects aren’t jeopardizing listed species; an analysis of nearly ninety thousand such consultations, published a few years ago in the Proceedings of the National Academy of Sciences, showed that none of the projects under discussion had been stopped or even extensively altered as a result of the consultations.

“When an animal or plant is declared endangered, the federal government has the authority to halt development projects in the species’ habitat,” Peter Alagona, a professor at the University of California-Santa Barbara, noted recently in Outside. “But the truth is that this very rarely happens.”

All of which is to say there are plenty of good reasons to modify the Act, but no good ones to weaken it. The value of earth’s biodiversity “is, quite literally, incalculable,” the House report stated, back in 1973. “Sheer self-interest impels us to be cautious.”