Seven millennia since its invention, leather remains one of the most durable and versatile natural materials. However, some consumers question the ethical ramifications and environmental sustainability of wearing products sourced from animals.

This shift in social standards is the main reason we’re seeing a wave of synthetic substitutes heading for the market.

Leather alternatives produced from synthetic polymers fare better in terms of environmental sustainability and have achieved considerable market share in recent years.

But these materials face the same disposal issues as any synthetic plastic. So, the leather market has begun to look to other innovations. As strange as it might sound, the latest contender is the humble fungus.

Research by my colleagues and I, published today in Nature Sustainability, investigates the history, manufacturing processes, cost, sustainability and material properties of fungus-derived renewable leather substitutes – comparing them to animal and synthetic leathers.

How unsustainable is animal leather, actually?

How sustainable leather is depends on how you look at it. As it uses animal skins, typically from cows, leather production is correlated with animal farming. Making it also requires environmentally toxic chemicals.

The livestock sector’s sustainability issues are well known. According to the United Nations Food and Agriculture Organisation, the sector is responsible for about 14% of all greenhouse emissions from human activity. Cattle rearing alone represents about 65% of those emissions.

Still, it’s worth noting the main product of cattle rearing is meat, not leather. Cow hides account for just 5-10% of the market value of a cow and about 7% of the animal’s weight.

There’s also no proven correlation between the demand for red meat and leather. So a reduction in the demand for leather may have no effect on the number of animals slaughtered for meat.