The walnut family once dominated European forests before disappearing during the ice ages

Gardening · Published 3 October 2026 Swipe more like this →

In short: Today, the walnut family is synonymous with global agriculture, but its history is written in ancient fossils. Once abundant across Central Europe, these trees were pushed to extinction by shifting climates and geographical barriers, leaving behind a legacy that researchers are only now decoding through genomic data and the fossil record.

The Juglandaceae family, encompassing walnuts, hickories, and wingnuts, boasts a deep evolutionary history. Fossil records reveal that these trees were once widespread across Central Europe, thriving in alluvial forests long before the Pleistocene ice ages began approximately 2.5 million years ago. Unlike North American species, which could migrate south to escape cooling climates, European populations were trapped by the Alps and the Mediterranean Sea, leading to their eventual disappearance from the region.

While many species vanished, the fossil record provides a detailed look at their former diversity. Carbonized nuts found in Rhine Valley sediments, dating back five million years, show that species like the butternut once had a vast distribution across Italy, the Netherlands, and Russia. Other genera, such as the wheel wingnut, have been traced back to the Paleocene, appearing shortly after the K-T boundary 65 million years ago. These findings illustrate a long transition from wind-dispersed ancestors to the charismatic nut-bearing trees recognized today.

Modern science is now bridging the gap between this ancient past and current economic utility. With over 60 species across eight to ten genera, the family is vital for its nutrient-rich nuts and high-grade timber. The Portal of Juglandaceae (PJU) has emerged as a critical hub for this research, integrating genomic, transcriptomic, and phenotypic data. By analyzing these sequences, scientists aim to solve biological mysteries, such as the molecular mechanisms behind high oil content and stress responses, which could prove essential for breeding more resilient varieties in a changing climate.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Hickory nuts grew thicker shells as defence against rodents
• The royal walnut tree has been traveling the Silk Road for two millennia.
• The Fagaceae family: Why oaks, beeches, and chestnuts rule the Northern Hemisphere forests
• The European beech is a forest giant with a surprisingly complex human history
• Seed dispersal innovations and ancient hybridization shaped the expansion of oak forests
• The California juniper is a rugged, multi-stemmed survivor of the American Southwest
• Why the world's most fragrant rice is losing its scent every single day
• The common juniper is a botanical record-breaker with a lifespan exceeding two millennia.
• From Hindu temples to Florida gardens, the sacred history of Ixora
• Why the alligator juniper is named for its thick, square-cracked, reptilian bark
• The ancient quillworts are living fossils that have barely changed in 200 million years.
• Is this Mediterranean shrub the original cedar mentioned by the ancient Greeks?

More in Plants · More in Gardening · Latest · A–Z · All topics