Enflo has earlier held positions at the Miller Institute for Basic Research in Science at the University of California, Berkeley, Stanford University, École Polytechnique, (Paris) and The Royal Institute of Technology, Stockholm.

In mathematics, Functional analysis is concerned with the study of vector spaces and operators acting upon them.

Hilbert spaces are of fundamental importance in many areas, including the mathematical formulation of quantum mechanics, stochastic processes, and time-series analysis.

At Stockholm University, Hans Rådström suggested that Enflo consider Hilbert's fifth problem in the spirit of functional analysis.

Enflo considered the problem of uniform embeddability among Banach spaces, and the distortion was an auxiliary device in his proof.

In 1972 Enflo proved that "every super-reflexive Banach space admits an equivalent uniformly convex norm".

The basis problem was posed by Stefan Banach in his book, Theory of Linear Operators.

Schauder bases can also be defined analogously in a general topological vector space.

Banach and other Polish mathematicians would work on mathematical problems at the Scottish Café.

On 6 November 1936, Stanisław Mazur posed a problem on representing continuous functions.

Formally writing down problem 153 in the Scottish Book, Mazur promised as the reward a "live goose", an especially rich price during the Great Depression and on the eve of World War II.

[12] Grothendieck's work on the theory of Banach spaces and continuous linear operators introduced the approximation property.

Grothendieck thus focused the attention of functional analysts on deciding whether every Banach space have the approximation property.

[13] In 1972, Per Enflo constructed a separable Banach space that lacks the approximation property and a Schauder basis.

[15] In functional analysis, one of the most prominent problems was the invariant subspace problem, which required the evaluation of the truth of the following proposition: For Banach spaces, the first example of an operator without an invariant subspace was constructed by Enflo.

Enflo proposed a solution to the invariant subspace problem in 1975, publishing an outline in 1976.

[16] In the 1990s, Enflo developed a "constructive" approach to the invariant subspace problem on Hilbert spaces.

[20] An essential idea in Enflo's construction was "concentration of polynomials at low degrees": For all positive integers

Anthropologists have been divided as to whether current human population evolved as one interconnected population (as postulated by the Multiregional Evolution hypothesis), or evolved only in East Africa, speciated, and then migrating out of Africa and replaced human populations in Eurasia (called the "Out of Africa" Model or the "Complete Replacement" Model).

Neanderthals and modern humans coexisted in Europe for several thousand years, but the duration of this period is uncertain.

[27] Neanderthals may have lived as recently as 24,000 years ago in refugia on the south coast of the Iberian peninsula such as Gorham's Cave.

[31] With Hawks and Wolpoff, Enflo published an explanation of fossil evidence on the DNA of Neanderthal and modern humans.

This article tries to resolve a debate in the evolution of modern humans between theories suggesting either multiregional and single African origins.

In particular, the extinction of Neanderthals could have happened due to waves of modern humans entered Europe – in technical terms, due to "the continuous influx of modern human DNA into the Neandertal gene pool.

"[32][33][34] Enflo has also written about the population dynamics of zebra mussels in Lake Erie.

[37] At age 12, Enflo appeared as a soloist with the Royal Opera Orchestra of Sweden.

Enflo's teachers included Bruno Seidlhofer, Géza Anda, and Gottfried Boon (who himself was a student of Arthur Schnabel).

[36] In 1999 Enflo competed in the first annual Van Cliburn Foundation's International Piano Competition for Outstanding Amateurs Archived 2009-04-19 at the Wayback Machine.

[38] Enflo performs regularly around Kent and in a Mozart series in Columbus, Ohio (with the Triune Festival Orchestra).

His solo piano recitals have appeared on the Classics Network of the radio station WOSU, which is sponsored by Ohio State University.